Exhibit 4.6

                                   TRANSLATION

                        FEDERAL COMMISSION OF ELECTRICITY

                                                   AGREEMENT NUMBER PIF-005/2003
                                            AMENDMENT AGREEMENT NUMBER 3 (THREE)

AMENDMENT AGREEMENT NUMBER 3 (THREE) TO THE MIXED AGREEMENT OF FINANCED PUBLIC
WORK NUMBER PIF-005/2003, ENTERED INTO BY AND BETWEEN ON THE ONE PART COMISION
FEDERAL DE ELECTRICIDAD (THE FEDERAL COMMISSION OF ELECTRICITY), REPRESENTED BY
ENG. EUGENIO LARIS ALANIS, IN HIS CAPACITY AS DIRECTOR OF FINANCED INVESTMENT
PROJECTS AND ON THE OTHER PART THE COMPANY CONSTRUCTORA INTERNACIONAL DE
INFRAESTRUCTURA, S.A. DE C.V., REPRESENTED BY ENG. LUIS HORCASITAS MANJARREZ, IN
HIS CAPACITY AS LEGAL REPRESENTATIVE, HEREINAFTER REFERRED TO AS THE
"COMMISSION" AND THE "CONTRACTOR", RESPECTIVELY, ACCORDING TO THE FOLLOWING
RECITALS AND CLAUSES:

                                    RECITALS

I. The PARTIES represent:

I.1   That on March 26, 2003, they executed the Mixed Agreement of Financed
      Public Work, recorded with the number PIF - 005/2003, legal instrument
      that shall hereinafter be referred to as the "Agreement", awarded to THE
      CONTRACTOR by means of the International Public Bidding Process,
      established by Articles 27, paragraph I, 28 and 30, paragraph II, 32, 33
      and 45 of the Law of Public Works and Services Related to the Same, which
      purpose consists of: the execution of the Civil Works, Electromechanical
      Works and Associated Works, supply, engineering, manufacturing,
      transportation, installation, testing and start up of two equipped
      turbo-generator Units, of 375 MW of nominal power each, for the fall and
      expense of specified design and that is detailed in Section 8 of the
      Bidding Rules, Works that all together are named the El Cajon
      Hydroelectric Project, and which principal structures are located in the
      Municipalities of La Yesca and Santa Maria del Oro, in the State of
      Nayarit of Mexico.



      The Works which consist in the Lump-sum Price Activities are described in
      detail in Exhibits OE-3, OE-4 and OE-5 of Section 4 of the Bidding Rules
      and are to be conducted under the lump-sum modality, inasmuch as the
      portion of the Works that correspond to the Lump-sum Activities are
      described in detail in Exhibit OE - 5A of Section 4 of the Bidding Rules
      and shall be executed under the base of unitary prices.

I.2   That the Price of the Agreement that THE COMMISSION agreed to pay to THE
      CONTRACTOR, agreed in Clause 9.1, was agreed to as total payment for the
      execution of the Works that correspond to the Lump-Sum Activities, the
      lump-sum price of US $682,517,584.80 Dollars (Six Hundred and Eighty Two
      Million Five Hundred and Seventeen Thousand Five Hundred and Eighty Four
      Dollars 80/100 Currency of the United States) plus Value Added Tax, and
      for the Unit Price Activities, the price of US $65,773,072.59 Dollars
      (Sixty Five Million Seven Hundred and Seventy Three Thousand Seventy Two
      Dollars 59/100 Currency of the United States) plus the corresponding value
      added tax.

I.3   That the beginning and development of the Works under the Execution
      Schedule, was agreed in Clause 13.1 of the "Agreement" in which THE
      CONTRACTOR was obliged to begin the works subject matter of the Agreement
      on March 26 2003 and to complete them on August 31st 2007, being the term
      for the completion of said works equal to 1620 days.

1.4   That on July 4 2003, THE PARTIES subscribed the Amendment Agreement number
      1 to the Agreement (hereinafter "Amendment Agreement number 1"), pursuant
      to the provisions of Articles 59 of the Law of Public Works and Services
      Related to the same, and 69 and 79 of its Regulations, in order to, (i)
      increase the amount of the Agreement exclusively on the basis of Unitary
      Prices Activities, referred to by clause 9.1 and derived only from various
      extraordinary works and additional works, which were not originally
      contemplated in the scope of the Project nor in the original Execution
      Schedule (hereinafter the "Additional Works"); (ii) agree on the Execution
      Schedule for the Additional Works; (iii) commit to analyze and to
      conciliate the new Execution Schedule



      and the displacement of Critical Events Dates, for the reasons therein
      established.

      That according to the provisions of Clause Third of the Amendment
      Agreement Number 1 THE COMMISSION and THE CONTRACTOR agreed to extend the
      original amount of the Unitary Prices Activities of the Agreement in the
      amount of $5,801,271.26 U.S. Dollars (Five million Eight Hundred and One
      Thousand Two hundred and seventy one Dollars 26/100 Currency of the United
      States), plus value added tax, which represented an increase of 8.82%
      (eight point eighty two per cent ) in connection with that originally
      agreed, resulting in an aggregate amount of the Agreement based on Unitary
      Prices of $71,574,343.85 U.S. Dollars (Seventy One Million Five Hundred
      and Seventy Four Thousand three hundred and forty three Dollars and
      85/100) plus the corresponding value added tax, according to the budget of
      the Additional Works.

1.5   That on September 10, 2003, the PARTIES executed the Amendment Agreement
      Number 2 to the Agreement (hereinafter the "Amendment Agreement Number 2")
      in accordance with that established in Articles 59 of the Law of Public
      Works and Services Related to the Same, and 69 and 79 of its Regulations,
      in order to: (i) under the Sixth Clause of the Amendment Agreement Number
      1, modify the original Execution Schedule due to the new date for the
      commencement of the Works that is April 24, 2003; (ii) agree to the
      displacement of the Critical Events Dates 1.1, 1.2, 1.3 and 1.4
      established in Exhibit Number 3 of the Agreement, derived from the
      modifications to the contractual conditions that have ruled up to this
      date according to Clause 13.1 of the Agreement; (iii) recognize and pay,
      if applicable, under the modality of unit prices the Additional Costs
      related to the modifications of the original Execution Schedule, as a
      consequence of the late delivery and under different conditions to those
      established in the Bidding Rules and in the Agreement, of the portals of
      the diversion tunnels and the access road to the Site, for causes not
      imputable to THE CONTRACTOR and adjust the Lump-sum Activities because of
      the diminution to the length of the diversion tunnels and the reduction of
      the volume of the cofferdam in the upstream waters; (iv) approval in the
      event THE COMMISSION decides their completion, of the payment of the
      Associated



      Additional Costs that derive from the Additional Works of Diversion under
      the modality of unitary prices for the building of the diversion tunnels
      and the pre- diversion tunnels by the left or right margins; (v) ratify in
      accordance with the Seventh Clause of the Amendment Agreement Number 1
      that the Critical Event 1.4 of Exhibit 3 of the Agreement ceased to be a
      Punishable Critical Event.

In accordance with that established in the Sixth Clause of the Amendment
Agreement Number 2 THE COMMISSION and THE CONTRACTOR agreed to increase the
original amount of the Lump-sum Activities of the Agreement, due to the
Additional Works of Diversion hereinafter described, subject to the condition
that THE COMMISSION decides their execution:

      -     The increase of resources and extension of the crossing tunnel
            equals the amount of US $ 1,810,899.51 Dollars (One Million Eight
            Hundred and Ten Thousand Eight Hundred and Ninety Nine Dollars
            51/100 Currency of the United States; plus VAT;

      -     Pre-diversion by the left bank equals the amount of US $
            2,969,437.75 Dollars (Two Million Nine Hundred and Sixty Nine
            Thousand Four Hundred and Thirty Seven Dollars 75/100 Currency of
            the United States) plus VAT;

      -     In the event THE COMMISSION decides not to execute the pre-diversion
            by the left bank, this shall pay for the endoorment of said tunnel
            the amount of $ 338,578.50 Dollars (Three Hundred and Thirty Eight
            Thousand Five Hundred and Seventy Eight Dollars 50/100 Currency of
            the United States) plus VAT;

      -     Pre-diversion by the right bank equals the amount of US $
            3,533,182.44 Dollars (Three Million Five Hundred and Thirty Three
            Thousand One Hundred and Eighty Two Dollars 44/100 Currency of the
            United States), plus VAT;

      -     In the event THE COMMISSION decides not to execute the pre-diversion
            by the right bank, THE COMMISSION shall pay for the construction of
            the access road, the ramp and the endoorment of said tunnel the
            amount of US $ 1,662,411.00 Dollars (One Million Six Hundred and
            Sixty Two Thousand



            Four Hundred and Eleven Dollars 00/100 Currency of the United
            States) plus VAT.

I.6   That the concept of Additional Costs agreed in the Amendment Agreement
      number 2 shall further include and without including any limitation
      whatsoever those derived from the following events:

      a)    The change of the trace of the baseboard, stated in official
            communication number LECAJ 1502/AGN/523/2004 of THE COMMISSION and
            the note to the Binnacle 438 of Contention Works, which defined the
            design of the foundation of the baseboard and its geometry between
            points 9 and 11 due to the geological conditions found in the river
            bed, after the Competitive Bidding and the execution of the
            Agreement as it appears in section 8.2.1.3 of the Bidding Rules and
            to the questions and answers of the bidders in the clarifications
            meetings, specifically to question number 47 made at such meeting.

      b)    The late commencement of the construction of the concrete face of
            the curtain for the reasons explained in the precedent paragraph.

1.7   That the Agreement and this Agreement are regulated by the Law of Public
      Works and Services Related to the same, its Regulations and other federal
      laws that result applicable, in accordance with Clause 31.1 of the
      Agreement.

1.8   That this instrument complies with the provisions of articles 59 of the
      Law of Public Works and Services Related to the Same, 69 and 79 of its
      Regulations where it stated that the Entities within their authorized
      investment plan, under their responsibility and due to express reasons
      duly grounded, may modify the mixed public works Agreements in those
      portions corresponding to the unitary prices by means of amendment
      agreements, provided that these, considered jointly or severally, do not
      surpass twenty five per cent of the amount or term agreed in the
      Agreement, do not imply essential variations to the original project, or
      they are entered to avoid in any manner the fulfillment of the Law or
      Treaties.



II.   THE COMMISSION represents that:

      It determined that it is necessary to amend the Agreement, therefore the
      execution of an Amendment Agreement (hereinafter the "Amendment
      Agreement") is necessary by virtue of the following:

II.1  To define and comply with the agreement provided in the First Clause
      paragraph (iv) of the Sixth Clause of the Amendment Agreement number 2 and
      set forth in section 1.5 of the Representations of this Agreement, and to
      the petition of THE COMMISSION and THE CONTRACTOR by means official
      communication no. FSC-1083/03 dated October 29 2003, and to begin the
      construction of the pre-diversion tunnel of the right bank, being the same
      completed and diverting the river on December 29 2003, which allowed the
      conclusion of the cofferdam waters upstream before the beginning of the
      raining season of 2004, preventing therefore that the Date for the
      Completion of the Project is deferred for one year.

II.2  It has considered to recognize to THE CONTRACTOR the affectations to the
      Execution Schedule approved in the Amendment Agreement number 2, and the
      in last paragraph of the Fourth Clause, inasmuch as THE COMMISSION ordered
      THE CONTRACTOR the construction of the pre-diversion by the right bank by
      means of the official communication FSC-1083/03 of October 29 2003, which
      determined the completion of the cofferdam waters upstream before the
      beginning of the raining season 2004.

II.3  The geological conditions foreseen for the construction of diversion
      tunnel no.1 aggravated by the intersection with the crossing tunnel,
      affected the advance in the excavation of tunnel 1 itself, provided THE
      CONTRACTOR, first had to incorporate resources and thereafter extend the
      crossing until tunnel 2 in order to be able to comply with the conclusion
      before July 10 2004, and to open fronts by this second tunnel.

II.4  In the river bed, in the zone of the displacement of the baseboard,
      between points 9 and 11, geological conditions different to those informed
      in the



      Bidding Rules, arose due to the presence of a fault-dam that was
      identified during the excavation of the river bed. This fault has been
      called "Calypso", and the solution by THE COMMISSION required a change of
      the project, in the structural trace and design of the baseboard.

      The foregoing is grounded in official communication number
      LECAJ1502/AGN/523/2004 of THE COMMISSION and the note of binnacle 438 of
      Contention Works, which define the structural trace and design of the
      foundation of the Baseboard.

II.5  Derived from the aforementioned representations, the Critical Events
      stated below were affected in the following manner:

      (i)   Critical Event 1.3 "Beginning of the construction of the tunnel of
            access to the enginehouse" due to the impossibility of beginning the
            construction of the cofferdam downstream, that is integrated to the
            curtain and is made a part of the critical event.

      (ii)  The critical event 1.5 "Beginning of the first stage of the pouring
            of the slabs of the concrete face of the curtain to an elevation of
            296", due to the execution of the pre-diversion tunnel by the right
            bank and the geological conditions located in the river bed, at the
            zone of excavation of the baseboard, between points 9 and 11;

      (iii) Critical Event 1.6 "Conclusion of the second stage of the pouring of
            the slabs of the concrete face of the curtain to an elevation of
            373.00", due to the reasons stated in the precedent paragraph.

      (iv)  Critical Event 1.12 "Beginning of the first pouring at the
            enginehouse for the electromechanical mounting" for the reasons
            stated in paragraph (i).

II.6  Notwithstanding the rights and obligations of the parties derived from the
      Agreement to this date, the Critical Events 1.2, 1.3, 1.4, and 1.10 of
      Exhibit 3 of the Agreement have been fulfilled under the binnacle note no.
      407 dated March 30 2004, set forth in commercial folio number 6 of book 6
      of the diversion works; the Binnacle note no. 53 dated January 15 2004,
      stated in folio number 26 of book 1 of the generation works; the Binnacle
      note no. 414 dated July 15



      2004, set forth in folio no. 27 of book 4 of the contention works and the
      Binnacle note number 10 dated August 23 2004, set forth in folio number 5
      of book 1 of the pressure tubing, respectively.

II.7  The execution of this Agreement is justified by the reasons stated in the
      precedent representations, and other considerations contained in the
      technical opinion which is made a part of this Agreement as Exhibit 1.

III.  THE CONTRACTOR represents that:

III.1 It agrees and acknowledges the extent of the amendments and clarifications
      subject matter of this Agreement, that it has legal capacity and it has
      the necessary organization and elements to comply with the same.

III.2 For the amendment of the Execution Schedule, which is attached hereto as
      Exhibit 5, THE CONTRACTOR has considered the actual advance to this date
      in the tunnel of access to the enginehouse, pressure tubing, relief tunnel
      and oscillation drift, as well as the change of the foundation of the
      baseboard and its geometry between the points 9 and 11, therefore it shall
      apply all its expertise, capabilities, skills and resources to maintain as
      the date for the conclusion of the Project foreseen on August 31 2007 the
      start up of Units 1 and 2 on February 28 and May 31st, respectively.

Thereafter THE PARTIES hereto agree to the execution of this Agreement under the
provisions of Article 59 of the Law of Public Works and Services Related to the
same, 69 and 79 of its Regulations and any other applicable rules and legal
provisions, and for such purposes they grant and submit to the following:

                                     CLAUSES

FIRST. - THE PARTIES agree that the subject matter of this Agreement is:

(i)   To modify the Execution Schedule of the Amendment Agreement number 2,
      under the provisions of Second and Third Clauses and in the last paragraph



      of the Fourth Clause of the Amendment Agreement number 2, as well as that
      stated in Recital number 1.6 and II of this Agreement and after having
      analyzed such geological conditions in the diversion tunnel no. 1, at the
      intersection with the crossing tunnel, the activities carried out for the
      execution of the pre-diversion by the left bank and the effect on the
      construction of the baseboard due to the Calypso fault, THE PARTIES agree
      to a new Execution Schedule for the Works attached hereto as Exhibit 5.

(ii)  To recognize the actual amount of the Additional Related Costs, derived
      from the execution of the Additional Diversion Works, ordered by THE
      COMMISSION under the modality of unitary prices, for the execution of the
      diversion tunnels and the pre-diversion tunnel by the right bank, as well
      as the works ordered by THE COMMISSION, for the possible pre-diversion by
      the left bank.

(iii) To cancel the amounts of the Additional Diversion Works indicated in the
      Sixth Clause of the Amendment Agreement number 2, which execution was not
      necessary.

(iv)  To recognize and pay, as the case may be, under the modality of unitary
      prices, the affectations of time and cost for the recovering of the
      schedule derived from that which has been stated in Representation number
      1.6 and the Representations of point II of this Agreement.

(v)   To define the new Dates for the Critical Events number 1.3, 1.5, 1.6 and
      1.12, provided in Exhibit number 3 of the Agreement, derived form the
      amendments to the contractual conditions that have applied until this
      date, according to Clauses 13.3 and 27.3 of the Second paragraph of the
      Agreement being attached hereto as Exhibit 4, replacing those indicated in
      Exhibit 3 of the Agreement.

(vi)  To determine the average daily proceeds that THE CONTRACTOR, under the
      Execution Schedule, shall execute for each one of the materials that form
      the enrockment dam in each one of the stages of its construction process,
      in



      order to comply with Critical Event 1.9 related to the "final closing of
      the diversion tunnels for the beginning of the filling of the impounding",
      which date is July 1st 2006, attached hereto as Exhibit 6.

SECOND. The new Execution Schedule of the Works, attached hereto as Exhibit 5 of
this Agreement, includes the formats OE10, OE11, OE11A and OE13 (Calendarized
activities net and critical route, Monthly Amount Schedule for the lump-sum
portion and Unitary Prices and Calendarized Disbursement Schedule of the
lump-sum portion of the monthly utilization of the materials and permanent
installation equipment) and OT-7 (General Project Plan) which replace formats
OE10, OE11, OE11A, OE13 and OT-7 of Exhibit 5 of the Amendment Agreement number
2, this adjustment is the result of the amendment of the Works Execution
Schedule and is essential for the fulfillment of the other terms and conditions
of the Agreement.

THE COMMISSION agrees, with the purpose of complying the aforementioned
Schedules, that the construction of the concrete face of the curtain be carried
out in three stages, in lieu of the two stages contemplated in the original
planning, according to that established in the format OE10, attached to this
document and according to this, the wording of Critical Events 1.5 and 1.6
changes in the following manner:

      1.5 Beginning of the first stage of the pouring of the slabs for the
      concrete face of the curtain to an elevation of 280.

      1.6 Termination of the third stage of the pouring of the slabs for the
      concrete face of the curtain to an elevation of 388.

THIRD. - According to Clause Sixth of the Amendment Agreement number 2 THE
PARTIES acknowledge to increase the original amount of the unitary prices
portion of the Agreement for the Additional Related Costs derived from the
execution of the following Additional Diversion Works ordered by THE COMMISSION
and that were actually completed:

(i)   Extension of the crossing tunnel from the connection of the tunnel 1 to
      the tunnel 2 the amount of this Additional work equals $261,145.08 U.S.
      Dollars



      (Two Hundred and Sixty One Thousand One Hundred and Forty Five Dollars
      08/100), plus VAT, according to the budget described in Exhibit 2 of this
      Agreement.

(ii)  The execution of the pre-diversion by the right bank, the amount of this
      Additional Work equals $1,457,047.88 U.S. Dollars (One Million Four
      Hundred and Fifty Seven Thousand Forty Seven Dollars 88/100), plus VAT,
      according to the budget specified in Exhibit 3 of this Agreement.

According to the above, there is an increase with respect to the original amount
of the Agreement Price in the portion related to the Unitary Prices Catalogue,
in the amount of $1,718,192.96 U.S. Dollars (One Million Seven Hundred and
Eighteen Thousand one Hundred and Ninety Two Dollars 96/100), which represents
2.6% (two point six percent) in increase with respect to the original amount of
the Agreement Price in the portion related to Unitary Prices and a 11.43 %
(eleven point forty three percent) accumulated with respect to the original
amount of the Agreement Price in the portion regarding the Unitary Prices,
resulting therefore an aggregate amount of the Unitary Prices Portion of the
Agreement, the amount of $73,292,536.81 U.S. Dollars (Seventy Three Million Two
Hundred and Ninety Two Thousand Five Hundred and Thirty Six Dollars 81/100) plus
VAT.

THE PARTIES acknowledge that the aforementioned amounts in paragraphs (i) and
(ii) replace and cancel all the amounts provided in the Sixth Clause of the
Amendment Agreement number 2, pending the conciliation, to be incorporated in
another agreement, of the additional resources of the pre-diversion by the left
and right banks.

FOURTH. - Notwithstanding the rights and obligations of the parties, derived
form the Agreement THE COMMISSION acknowledges that the critical events 1.2,
1.3, 1.4, and 1.10 of Exhibit 3 of the Agreement have already been fulfilled.

FIFTH. - THE PARTIES agree that the new dates for the Critical Events 1.3, 1.5,
1.6, and 1.12 of Exhibit 3 of the Agreement, derived form the amendments to the
covenants in effect to this date under Clause 13.1 of the Agreement, and that
are



attached hereto as Exhibit 4, replacing those indicated in Exhibit 3 of the
Agreement.

SIXTH. - THE CONTRACTOR according to the Execution Schedule shall place the
average volumes provided in Exhibit 6 of this Agreement of each of the materials
that form the enrockment dam in each one of the stages of its construction
process.

SEVENTH. - Due to the delay that suffered the construction of tunnel 1, as
consequence of the geological fault located at the intersection with the
crossing tunnel and to the geological fault (Calypso) found in the river bed
between points P9 and P11 of the baseboard, the beginning of the construction of
the baseboard in the river bed was delayed, due to causes not imputable to THE
CONTRACTOR.

THE PARTIES, agree to analyze also, the problems caused by the excavation of the
channel of the so called outlet work, which product used to spill over the right
bank and to review and authorize in due course, as the case may be, within sixty
days of the filing of the petition by THE CONTRACTOR, the affectations that may
arise, to comply with the date stated in critical event no. 1.9 on July 1st
2006. It is made clear that for the preparation of the Execution Schedule the
days of the delay derived from these unforeseeable events were not take into
account.

EIGHTH. The monthly advances of the concepts covered by this Agreement that
correspond to works to be executed, including the Additional Costs mentioned in
the First Clause Paragraph (ii) of this Agreement and the Additional Related
Costs defined in the Amendment Agreement number 2, shall have the same treatment
of recognition and form of payment as those set forth by the Agreement for the
Unitary Prices Activities according to clauses 9.2, 10.1 and 13.4, THE
COMMISSION will recognize them in an independent manner according to Exhibit 14
of the Agreement and to the First and Second Memorandum of Clarifications to the
Agreement, that is to say, as if they were an event of recognition of advances
in the construction provided in the economic format OE-11B.



NINTH. For every Additional Costs, Additional Related Costs as they were defined
in the Amendment Agreement number 2 and those additional costs derived from this
Agreement, under section 1.6 of the Recitals and the First Clause paragraph (ii)
of this Agreement, THE PARTIES commit to conciliate them within a term no longer
than 60 days as of their submission by THE CONTRACTOR, who will include them in
the Report of the Monthly Advance of the month following to that such
conciliation is made.

TENTH.- According to the provisions of Representation III.1 of this Agreement,
in the event that due to an Act of God or Force Majeur event or to a
Governmental Force Majeur event or to an event of default by THE COMMISSION, the
additional or outstanding works ordered by THE COMMISSION, Real Estate Rights,
Site Conditions differing from the ones provided for the project in terms of
section 8 of the Bidding Rules, prevent the obtaining of the results of the new
Execution Schedule and this prevents the conclusion of the Critical Event 1.9 of
Exhibit 3 of the Agreement "Final Closing of the diversion tunnels for the
beginning of the filing of the impounding", no later than on July 1st 2006, both
Parties, according to that indicated in Clauses 26.5, 27.3 and other applicable
of the Contract, shall analyze, conciliate and formalize a new Execution
Schedule, including Exhibit 3 of the Agreement, within a term of thirty (30)
days counted as of the date on which the termination of the Critical Event 1.9
of Exhibit 3 of the Agreement called "Final Closing of the diversion tunnels for
the beginning of the filling of the impounding" should have taken place, for
such purpose the possible limitations to the financing of THE CONTRACTOR should
be taken into account, and that THE COMMISSION shall absorb, abiding to the
Agreement, in the event that what is foreseen by this Clause arises, the
financial costs of an extension to the Execution Schedule, considering the
provisions of said Clause 26.5 of the Agreement and as of the expiration of the
60 days term provided for in the same and up to a term of the extension of the
Execution Schedule agreed. In this case, the application of the penalties for
THE CONTRACTOR foreseen in Clauses 13.6 and 26.1 of the Agreement shall not
apply nor those of the Law of Public Works and Services Related to the same and
its Regulations shall apply during the extension term agreed by THE PARTIES.



ELEVENTH. - The PARTIES agree that the amount of the Compliance Guarantee
granted by THE CONTRACTOR for an amount equivalent to ten percent (10 %) of he
amount of the authorized investment for the second fiscal year, is sufficient to
guarantee the due, proper and absolute fulfillment by THE CONTRACTOR of all its
obligations derived from the Agreement and this Amendment Agreement for the
current fiscal year, inasmuch as the Works Execution Schedule originally agreed
was adjusted as consequence of that agreed in the Amendment Agreement.

TWELFTH. - The execution of this Agreement does not represent a waiver to the
rights available to THE CONTRACTOR, derived from the execution of the works in
the terms established in the Bidding Rules, in the Agreement, and in the
Amendment Agreements numbers 1 and 2 nor of any other situation prior to the
execution of this Amendment Agreement.

THIRTEENTH. - THE PARTIES agree that, except for that expressly provided for in
this Amendment Agreement, the rest of the Clauses that are made a part of the
Agreement and its Amendment Agreements are mandatory, and they shall rule in
full force and effect.

The terms used with capital letters in this document shall have the same meaning
as the one given to them in Clause 1.1 of the Agreement and in the First, Second
and Third Amendment Agreements, except as otherwise expressly specified in this
Amendment Agreement.

IN WITNESS OF THE ABOVE, THE PARTIES execute and deliver, through their legally
authorized representatives, this Amendment Agreement, in six counterparts
equally valid, in Mexico City, Federal District, on the 30th day of September
two thousand and four.

By the "COMMISSION"                                 By the "CONTRACTOR"

(An illegible signature)                   (An illegible signature)
- -------------------------------------      -------------------------------------



MR. EUGENIO LARIS ALANIS                   MR. LUIS HORCASITAS MANJARREZ
MANAGER OF PROJECTS OF                     LEGAL REPRESENTATIVE
FINANCED INVESTMENTS



LIST OF EXHIBITS:

EXHIBIT Num. 1- Technical Report
EXHIBIT Num. 2- Extension of the crossing tunnel (catalogue)
EXHIBIT Num. 3- Pre-diversion by the right bank (Catalogue)
EXHIBIT Num. 4- Dates of Critical Events
EXHIBIT Num. 5- Works Schedule Amendment Agreement num. 3
EXHIBIT Num. 6- Results of collocation of materials in the curtain, to comply
                   with Critical Event 1.9