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                                                                    Exhibit 10.6
                           FIRST AMENDMENT AGREEMENT

         This First Amendment Agreement, effective as of June 16, 1995 (this
"Amendment"), is by and among (i) Union Texas Petroleum Holdings, Inc., a
Delaware corporation ("Company"), (ii) the undersigned lenders ("Banks") which
are parties to the Credit Agreement dated as of April 24, 1995 (the
"Agreement") among the Company, the lenders party thereto, NationsBank of
Texas, N.A., as agent ("Agent"), and the Co-Agents named therein, (iii) the
Agent and (iv) the Co-Agents.  In consideration of the mutual covenants
contained herein, the Company, the Banks, the Co-Agents and the Agent agree as
set forth herein.

         1.      Amendments to Credit Agreement.  The Agreement is hereby
amended as follows:

                 1.1.  Section 1.01.  The following respective definitions set
forth in Section 1.01 of the Agreement are hereby amended to read as follows:

                 "Adjusted Equity" means the consolidated stockholders equity
         of the Company and its Consolidated Subsidiaries, as determined on a
         consolidated basis in accordance with generally accepted accounting
         principles, adjusted to exclude (i) any cumulative foreign exchange
         translation adjustments, (ii) any non-cash write-up or writedown of
         any assets of the Company and its Consolidated Subsidiaries made after
         March 31, 1995 in accordance with generally accepted accounting
         principles, and (iii) the non-cash effect of the adoption of any
         change after March 31, 1995 required by generally accepted accounting
         principles.

                 "Margin Increase Condition" exists at all times during which
         any senior unsecured long-term debt of the Company is rated below BBB-
         by S&P.

         Section 1.01 of the Agreement is hereby further amended by deleting
therefrom the definitions of "Additional Margin Increase Condition" and "Margin
Period".

                 1.2.     Section 2.07(a).  The first sentence of Section
2.07(a) of the Agreement is hereby amended to read as follows:

                 (a)      If such Loan is a Base Rate Loan, for each day that
such Loan is a Base Rate Loan, at a rate per annum equal to the sum of (i) the
Base Rate for such day plus (ii) at such times as the Margin Increase Condition
exists, 1/4% plus (iii) at such times as any Event of Default exists, 1%.

                 1.3.     Section 2.07(b).  The first sentence of Section
2.07(b) is hereby amended to read as follows:
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                 (a)      If such Loan is a Euro-Dollar Loan, at a rate per
annum equal at all times during any Interest Period for such Loan to the sum of
(i) 0.6875% plus (ii) the applicable London Interbank Offered Rate plus (iii)
at such times as the Margin Increase Condition exists, 1/4% plus (iv) at such
times as any Event of Default exists, 1%; provided that any overdue principal
of or interest on any Euro-Dollar Loan shall bear interest, payable on demand,
for each day from and including the date payment thereof was due to but
excluding the date of actual payment, at a rate per annum equal to the sum of
1% plus the higher of (i) the sum of 0.6875% plus the London Interbank Offered
Rate applicable to such Loan plus at such times as the Margin Increase
Condition exists, 1/4% and (ii) the sum of (1) 0.6875% plus (2) the average
(rounded upward, if necessary, to the next higher 1/16 of 1%) of the respective
rates per annum at which one day (or, if such amount due remains unpaid more
than three Euro-Dollar Business Days, then for such other period of time not
longer than three months as the Agent may select) deposits in dollars in an
amount approximately equal to such overdue payment due to each of the Reference
Banks are offered to such Reference Bank in the London interbank market for the
applicable period determined as provided above plus (3) at such times as the
Margin Increase Condition exists, 1/4% (or, if the circumstances described in
clause (a) or (b) of Section 8.01 shall exist, at a rate per annum equal to the
sum of 1% plus the rate applicable to Base Rate Loans for such day).

                 1.4.     Section 5.01(d).  Section 5.01(d) of the Agreement is
hereby amended to read as follows:

                 (d)      as soon as available and in any event within 60 days
         after the end of each fiscal quarter of the Company, a certificate of
         the chief financial officer, the chief accounting officer or the
         treasurer of the Company certifying (i) whether the Margin Increase
         Condition exists as of the date of such certificate, (ii) the Unimar
         Percentage as of the end of such quarter and the amounts as of the end
         of such quarter of Consolidated Debt, Defeased Debt, Excluded
         Subordinated Debt, Debt of the Company and its Consolidated
         Subsidiaries determined on a consolidated basis, Debt of the Company
         and the Restricted Subsidiaries determined on a consolidated basis,
         Debt of Unimar, Debt of Unrestricted Subsidiaries, Excess Letter of
         Credit/Guarantee Amount, Non-Restricted Asset Non-Recourse Debt,
         Non-Recourse Debt of the Company and the Restricted Subsidiaries, and
         Restricted Subsidiaries Recourse Debt, and (iii) each Asset Sale that
         has been consummated during such quarter, the Fair Market Value of the
         Restricted Assets subject thereto, the amount of fees, commissions,
         expenses and taxes related thereto, the Net Sales Proceeds therefrom
         and the cumulative amount of the Excess Net Sales Proceeds from all
         Assets Sales since December 31, 1993;

                 1.5.     Section 5.05(a).  Section 5.05(a) of the Agreement is
hereby deleted from the Agreement.





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                 1.6.     Section 5.15.  Section 5.15 of the Agreement is
hereby amended by changing the amount "$300,000,000" set forth therein to
"$350,000,000".

                 1.7.     Section 9.05.  Section 9.05 of the Agreement is
hereby amended by deleting the second proviso thereof (which pertains to
amendments to or waivers of Section 5.05(a)).

         2.      Effectiveness.  The effectiveness of this Amendment is subject
to the receipt by the Agent of:

                 2.1.     counterparts of this Amendment signed by each of the
         parties hereto (or, in the case of any party as to which an executed
         counterpart shall not have been received, receipt by the Agent in form
         satisfactory to it of telegraphic, telex or other written confirmation
         from such party of execution of a counterpart hereof by such party);
         and

                 2.2.     a consent, duly executed by each of the Required
         Guarantors, substantially in the form of Exhibit A hereto.

         3.      Miscellaneous.

                 3.1.  Amendments, Etc.  No amendment or waiver of any
provision of this Amendment, nor consent to any departure by the Company
therefrom, shall in any event be effective unless effected in accordance with
Section 9.05 of the Agreement.

                 3.2.  Governing Law.  This Amendment and the Agreement as
amended hereby shall be construed in accordance with and governed by the laws
of the State of Texas.

                 3.3.  Preservation.  Except as specifically modified by the
terms of this Amendment, all of the terms, provisions, covenants, warranties
and agreements contained in the Agreement (including, without limitation,
exhibits thereto) or any other Financing Document remain in full force and
effect.  Undefined capitalized terms used herein are used herein as defined in
the Agreement as amended hereby.

                 3.4.  Execution in Counterparts.  This Amendment may be
executed in any number of counterparts, each of which when so executed shall be
deemed to be an original, with the same effect as if the signatures thereto and
hereto were upon the same instrument.

                 3.5.  Representations and Warranties.  The Company hereby
represents and warrants to the Banks, the Co-Agents and the Agent that (i) the
representations and warranties contained in Article IV of the Agreement (other
than the representations and





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warranties contained in Sections 4.04(a) and 4.04(c) thereof) are correct on
and as of the date hereof as though made on and as of the date hereof, with
this Amendment and the Agreement as amended hereby, constituting "Financing
Documents" for purposes thereof, and (ii) no event has occurred and is
continuing which constitutes a Default or an Event of Default.

                 3.6.  Default.  Without limiting any other event which may
constitute an Event of Default, in the event that any representation or
warranty set forth herein shall be incorrect or misleading in any material
respect when made, such event shall constitute an "Event of Default" under the
Agreement, as amended hereby.

                 IN WITNESS WHEREOF, the parties hereto have caused this
Amendment to be executed by their respective officers thereunto duly
authorized, as of the date first above written.

                                        UNION TEXAS PETROLEUM HOLDINGS, INC.


                                        By: /s/ M.N. MARKOWITZ
                                            ----------------------------
                                            M.N. Markowitz
                                            Vice President and Treasurer


BANKS:

NATIONSBANK OF TEXAS, N.A.              UNION BANK OF SWITZERLAND,
                                        HOUSTON AGENCY

By:   /s/ PAUL A. SQUIRES       
    -----------------------------
      Paul A. Squires                By:      /s/ EVANS SWANN      
      Senior Vice President                 ----------------------------
                                              Evans Swann
                                              Managing Director
         

BANK OF AMERICA NATIONAL                By:   /s/ DAN O. BOYLE
TRUST AND SAVINGS ASSOCIATION               ----------------------------
                                              Dan O. Boyle
                                              Vice President

By:      /s/ LAURA B. SHEPARD
    -----------------------------       THE BANK OF NOVA SCOTIA
         Authorized Officer

                                        By:   /s/ [Illegible]       
                                            ----------------------------
                                              Authorized Officer





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CHEMICAL BANK                                    BANQUE NATIONALE DE PARIS,
                                                 HOUSTON AGENCY
                                            
By:      /s/ [Illegible]                         By:   /s/ [Illegible]
    ---------------------------                      -----------------------
         Authorized Officer                            Authorized Officer
                                            
CREDIT LYONNAIS CAYMAN                      
ISLAND BRANCH                                    LTCB TRUST COMPANY
                                            
                                            
By:      /s/ XAVIER RATOUIS                      By:   /s/ [Illegible]
    ---------------------------                      -----------------------
         Authorized Officer                            Authorized Officer
                                            
                                            
THE FIRST NATIONAL BANK OF                       SOCIETE GENERALE, SOUTHWEST
CHICAGO                                          AGENCY
                                            
                                            
By:      /s/ [Illegible]                         By:   /s/ [Illegible]
    ---------------------------                      -----------------------
         Authorized Agent                              Authorized Officer
                                            
                                            
MELLON BANK, N.A.                                THE BANK OF TOKYO, LTD.,
                                                 DALLAS AGENCY
                                            
By:      /s/ A. J. SABATELLE                     By:   /s/ JOHN M. MCINTYRE
    ---------------------------                      -----------------------
         Authorized Officer                            Authorized Officer
                                            
MORGAN GUARANTY TRUST                       
COMPANY OF NEW YORK                              BANQUE PARIBAS, HOUSTON
                                                 AGENCY
                                            
By:      /s/ JOHN KOWALCZUK                      By:   /s/ [Illegible]
    ---------------------------                      -----------------------
         Authorized Officer                            Authorized Officer
                                            
                                            
                                                 By:   /s/ BART SCHOUEST
                                                     -----------------------
                                                       Authorized Officer
                                            
                                            
                                            
                                            


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CHRISTIANIA BANK                                NATIONAL WESTMINSTER BANK
                                                PLC (NEW YORK BRANCH)

By:    /s/ JAHN O. ROISING                      By:    /s/ [Illegible]
    ---------------------------                     ---------------------------
       Authorized Officer                              Authorized Officer

By:    /s/ [Illegible]                                                          
    ---------------------------                 NATIONAL WESTMINSTER BANK      
       Authorized Officer                       PLC (NASSAU BRANCH)            
                                                                               
                                                                               
                                                                               
CITIBANK, N.A.                                  By:    /s/ [Illegible]        
                                                     --------------------------
                                                       Authorized Officer     
                                                                               
                                                                               
By:     /s/ BARBARA A. COHEN                    THE YASUDA TRUST AND BANKING  
    ---------------------------                 COMPANY, LIMITED, NEW YORK    
        Barbara A. Cohen                        BRANCH                        
        Vice President                                                         
                                                                               
DRESDNER BANK AG, NEW YORK                      By:    /s/ GERALD GILL
AND GRAND CAYMAN BRANCHES                           --------------------------- 
                                                       Authorized Officer     
                                                                               
                                                                               
By:    /s/ [Illegible]                          BANK OF TAIWAN                
    ---------------------------                                                
       Authorized Officer                                                      
                                                By:    /s/ [Illegible]        
                                                    ---------------------------
By:    /s/ B. C. ERICKSON                              Authorized Officer     
    ---------------------------                                                
       Authorized Officer                                                      
                                                BANQUE FRANCAISE DU           
THE MITSUBISHI TRUST &                          COMMERCE EXTERIEUR            
BANKING CORPORATION                                                            
                                                By:    /s/ IAIN A. WHYTE      
                                                    ---------------------------
By:    /s/ [Illegible]                                 Iain A. Whyte          
    ---------------------------                        Assistant Vice President
       Authorized Officer                                                      
                                                                               
                                                By:    /s/ MARK A. HARRINGTON 
                                                    ---------------------------
                                                       Mark A. Harrington     
                                                       Vice President &       
                                                       Regional Manager       
                                                                               
                                                                               
                                                                     
                                                                               
                                                                               
                                                                               
                                                                               
                                                                               
                                                                               
                                                                               
                                                                               
                                                


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DEN NORSKE BANK AS                                FIRST INTERSTATE BANK OF
                                                  TEXAS, N.A.
                                         
By:    /s/ EDWARD L. METE                         By:    /s/ COLLIE C. MICHAELS
    ---------------------------                       -------------------------
       Edward L. Mete                                    Authorized Officer
       Senior Vice President             
                                         
                                         
By:    /s/ FRAN MEYERS                   
    ---------------------------                                               
       Fran Meyers                       
       Vice President                    
                                                   
                                         
                                                  NATIONSBANK OF TEXAS, N.A.,
                                                  as Agent
                                         
                                         
                                                  By:    /s/ PAUL A. SQUIRES
                                                      -------------------------
                                                         Paul A. Squires
                                                         Senior Vice President
                                         
                                         
                                         
BANK OF AMERICA NATIONAL                          UNION BANK OF SWITZERLAND, 
TRUST AND SAVINGS                                 HOUSTON AGENCY, as         
ASSOCIATION, as Co-Agent                          Co-Agent                   
                                                                              
                                         
By:    /s/ LAURA B. SHEPARD                       By:    /s/ EVANS SWANN
    ---------------------------                       -------------------------
       Authorized Officer                                Evans Swann
                                                         Managing Director
                                         
                                         
                                         
                                                  By:    /s/ DAN O. BOYLE
                                                      -------------------------
                                                         Dan O. Boyle
                                                         Vice President
                                         
                                         
                                         
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                                                                     EXHIBIT A


                          ACKNOWLEDGEMENT AND CONSENT
                                 June 16, 1995

                 Reference is made to the Credit Agreement dated as of April
24, 1995 (the "Credit Agreement"), among Union Texas Petroleum Holdings, Inc.,
a Delaware corporation ("Company"), the Banks and Co-Agents parties thereto,
and NationsBank of Texas, N.A., as Agent ("Agent") and to the First Amendment
Agreement dated as of June 16, 1995 (the "Amendment") among the Company, the
Banks and Co-Agents parties thereto, and the Agent.  Undefined capitalized
terms are used herein as defined in the Credit Agreement as amended by the
Amendment (the "Amended Credit Agreement").

                 To induce the Agent and the Banks to execute the Amendment,
each of the undersigned Subsidiary Guarantors hereby (a) acknowledges the
execution, delivery and performance of the Amendment by the Company, (b) agrees
that (i) none of such Subsidiary Guarantor's obligations under or in connection
with the Subsidiary Guaranty Agreement and none of the Banks' or the Agent's
rights and remedies with respect to any Subsidiary Guarantor is released,
impaired or affected thereby or by the foregoing, (ii) the Subsidiary Guaranty
Agreement is not released, impaired or affected thereby or by any of the
foregoing, and (iii) this acknowledgement shall not be construed as requiring
the consent or agreement of any Subsidiary Guarantor in any circumstance, (c)
ratifies and confirms all provisions of the Subsidiary Guaranty Agreement, and
(d) agrees that none of such Subsidiary Guarantor's obligations, none of the
Banks' or the Agent's rights and remedies nor the Subsidiary Guaranty
Agreement, would be released, impaired or affected if such Subsidiary Guarantor
had not executed this Acknowledgment and Consent.

                 IN WITNESS WHEREOF, the parties hereto have caused this
Acknowledgement and Consent to be duly executed and delivered by their
respective officers thereunto duly authorized, as of the 16th day of June,
1995.

SUBSIDIARY GUARANTORS:


UNION TEXAS PETROLEUM                                  UNION TEXAS PRODUCTS
ENERGY CORPORATION                                     CORPORATION


By:                                                    By:         
    ---------------------------                           ----------------------
         M.N. Markowitz                                        M.N. Markowitz
         Treasurer                                             Treasurer






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                                                                       EXHIBIT A


UNION TEXAS EAST                                       UNION TEXAS INTERNATIONAL
KALIMANTAN LIMITED                                     CORPORATION


By:                                                    By:          
    ---------------------------                            --------------------
         M.N. Markowitz                                        M.N. Markowitz
         Treasurer                                             Treasurer


                                                       UNISTAR, INC.


                                                       By:          
                                                           --------------------
                                                               M.N. Markowitz
                                                               Vice President






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