Exhibit 10.35.4

STANDSTILL AGREEMENT

     THIS AGREEMENT  effective as provided  herein by and between  ENVIRONMENTAL
REMEDIATION HOLDING CORPORATION ("ERHC"), a Colorado  corporation,  with offices
at 1686 General  Mouton Avenue,  Lafayette,  LA 70508 and the Investors or their
permitted assigns whose names are included in Schedule A annexed hereto and made
a part hereof (collectively the "Investors" or individually, the "Investor").

     WHEREAS,  ERHC issued its 12.0% convertible notes due on the earlier of the
date upon  which the  Company  received  debt or equity  financing  in excess of
$4,000,000  or December 31, 1999 (the  "Notes) and granted  warrants to purchase
ERHC's  common  stock  with an  exercise  date on or before  June 18,  2002 (the
"Warrants"); and

     WHEREAS,  ERHC has  executed  and its Board of  Directors  have  approved a
letter of intent  dated April 8, 1999 with ERHC  Investment  Group,  Inc.  which
requires certain consents from the Investors and amendments and modifications to
the Notes and the Warrants,  a copy of which letter of intent is annexed  hereto
and made a part hereof as Exhibit A (the "Letter of Intent"); and

     WHEREAS,  the parties wish to confirm in writing  their  understanding  and
agreement regarding these matter.

     NOW THEREFORE in consideration of the mutual promises  contained herein and
for other good and valuable consideration, the receipt and adequacy of which are
hereby acknowledged, the parties agree as follows:

1.   Confidential   Information.   Investors'   consent   and   amendments   and
     modifications to the Notes and Warrants as provided in the Letter of Intent
     are conditions  precedent to the Initial  Closing.  This is due to the fact
     that the Notes and Warrants  have certain  adjustments  which may render it
     impossible for ERHC to issue the requisite  control interest required under
     the term of the Letter of Intent.  The matters  contained herein and in the
     Letter of Intent are confidential  information not available to the public.
     These  matters  will only be made public with a filing by ERHC of a Form 8K
     within the time required from the Initial  Closing as defined in the Letter
     of Intent  (the  "Initial  Closing"),  the date on which an 8K event  takes
     place.  Accordingly,  the Investors expressly agree not to disclose, use or
     trade on this information either directly or indirectly in any manner until
     such time as the Form 8K reporting  this Letter of Intent is filed with the
     SEC.

2.   Amendments and  Modifications.  From the date of the Initial  Closing under
     the Letter of Intent,  it is agreed that the following terms and conditions
     are amended and modified:







     A.   The Notes are amended and modified as follows:

          1.   The provision for payment of interest contained in paragraph 1(b)
               is deleted  and in its place shall read  "Interest  on the unpaid
               balance of this Note at the rate of twelve  percent  (12.0%)  per
               annum  shall  accrue from the date hereof and shall be payable on
               the earlier of (i) the Maturity Date or (ii) the Conversion  Date
               as to all or that portion of the Note converted in cash or in the
               form of shares in common  stock in an amount  equal to the amount
               of interest due divided by the Conversion  Price. The Company may
               elect to make accrued  interest  payments at any time in the form
               of  shares in common  stock in an amount  equal to the  amount of
               interest due to date  divided by the  Conversion  Price.  In such
               event,  only interest  which  accrues from such election  payment
               shall be payable on any  subsequent  election date or on maturity
               or conversion."

          2.   In addition to the  amendment to paragraph  1(b),  the  following
               will be  added  to such  paragraph:  "Notwithstanding  any  other
               provision  contained in this paragraph  1(b),  interest is waived
               from the date of the Initial Closing and thereafter until October
               15, 1999.

          3.   The  provisions for voluntary  conversion  contained in paragraph
               4(a) is amended to permit,  in addition to conversion of all or a
               portion of the Notes, for the conversion of outstanding  interest
               and penalties,  if any, into Common Stock at the time a voluntary
               conversion of principal is made for the amount of interest due on
               the Notes.

          4.   The Conversion Price in paragraph 4(b) of the Notes is amended to
               be $0.25.

     C.   In  addition  to  the  foregoing  amendments  and  modifications,  the
          Investors consent and agree to the following additional terms:

          1.   From the date of the Initial Closing and thereafter until October
               15,  1999 (i) not to convert  all or any part of the Notes,  (ii)
               not to declare a default  or seek  acceleration  of any  payments
               under the Notes, (iii) not to commence any collections actions or
               proceedings  under the Notes (iv) not to commence any foreclosure
               or bankruptcy  actions under the Notes and (v) not to declare any
               Event of Default or commence  any  arbitration  action  under the
               Notes or Warrants.

          2.   From the date of execution of this Agreement, to waive all rights
               under any  adjustments,  antidilution  provisions  or  preemptive
               rights previously granted in the Notes or Warrants or provided by
               these amendments  and  modifications (i)  relative to the






               transaction contemplated in the Letter of Intent or (ii) relative
               to any  settlement  with  Procura  Financial  entered into by the
               Company upon  commercially  reasonable to complete the assignment
               of all  rights,  title and  interest  in Sao Tome in favor of the
               Company.

          3.   Through the Initial Closing, to accept shares of Common Stock for
               all accrued and unpaid  interest and penalties on the Notes as of
               the Initial  Closing,  which shares shall be delivered within ten
               (10) days of the Closing Date.

          4.   In consideration for the reduction in the Conversion Price of the
               Notes,  each  Investor  waives  any and all  claims  relative  to
               additional warrants which may or may not have been required to be
               granted under the terms of the Term Sheet for this offering.

          5.   From the date of execution of this Agreement and thereafter until
               October 15, 1999,  to vote with the Company in the event that any
               third  party,  other  than  each of the  other  note and  warrant
               holders listed as a Selling Shareholder in Amendment No. 3 to the
               Form S- 1  filed  with  the  SEC,  commences  any  bankruptcy  or
               foreclosure action against the Company or any of its subsidiaries

3.   Effects  of No Closing  under the  Letter of  Intent.  In the event that no
     Closing as defined in the Letter of Intent (the  "Closing")  occurs  within
     ninety  (90) days from the date of the  Initial  Closing,  the  amendments,
     modifications  and  consents in paragraph 2 above shall be null and void ab
     initio.

4.   ERHC Representations and Warranties.  ERHC represents and warrants that the
     amendments,  modifications  and  consents  set  forth  in  paragraph  2 are
     substantially similar to the amendments,  modifications and consents sought
     from each of the  other  convertible  note and  warrant  holders  listed as
     Selling  Shareholders in the Amendment No. 3 to the Form S-1 filed with the
     SEC and differ only in those matters  which are specific to any  particular
     note or warrant transaction listed therein.

5.   Effect upon Other Terms and Conditions.  Notwithstanding the amendments and
     modifications  contained  herein,  it is  expressly  agreed by the  parties
     hereto that all other terms,  conditions  and  provisions  of the Notes and
     Warrants remain in full force and effect.

6.   Ratification.  The Investors ratify the acts of and hold harmless the Board
     of Directors and Officers for all actions taken by them in compliance  with
     the  interpretations  of any  court  of  competent  jurisdiction  as to the
     application  of the  Business  Judgement  Rule from  inception  through the
     Initial Closing Date.







7.   Intended  Beneficiaries.  ERHC  and  ERHC  Investment  Group  Inc.  are the
     intended  beneficiaries of this Agreement.  In the event of any breach, the
     parties and the intended  beneficiaries  of this  Agreement  shall have all
     remedies  available  at  law or in  equity  including  the  right  to  seek
     injunctive relief.

8.   Effective Date. This Agreement shall be effective and binding upon ERHC and
     the each  Investor  set forth in Schedule A  individually  from the date of
     execution by each Investor.

9.   Binding Obligations.  The obligations of the parties set forth herein shall
     be binding upon and inure to the benefit of each party's heirs,  executors,
     administrators, beneficiaries, transferees, successors and assigns.

10.  Governing Law,  Jurisdiction and Venue. The governing law, jurisdiction and
     venue set forth in the Notes and  Warrants  shall  remain in full force and
     effect.

11.  Counterparts.  This  Agreement may be executed in one or more  counterpart,
     each of which when taken  together shall  represent one binding  agreement.
     Delivery  of an  executed  counterpart  hereof via  telecopier  shall be as
     effective as delivery of a manually executed counterpart hereof.

     IN  WITNESS  WHEREOF,  each  party set  their  hand and seal  effective  as
provided herein.

                             ENVIRONMENTAL REMEDIATION HOLDING CORPORATION
                                  By: /s/ JAMES A. GRIFFIN
                                  -------------------------
                                  James A. Griffin, Secretary

                             INVESTOR:

Execution Date: April 21, 1999      By: /s/ AZRIEL NAGAR
                                    --------------------
                                    Signature and Title
                                    Print Name: Azriel Nagar

Execution Date: May 5, 1999         By: /s/ EDWARD REHQUIN
                                    ----------------------
                                    Signature and Title
                                    Print Name: Edward Rehquin
                                    Print Title: President

Execution Date: April 22, 1999      By: /s/ JOSEPH GRIFFIN SPANO
                                    ----------------------------
                                    Signature and Title
                                    Print Name: Joseph Griffin Spano

Execution Date:    , 1999           By: /s/ DAVID B.  THORNBURGH
                                    ----------------------------
                                    Signature and Title
                                    Print Name: David B.  Thornburgh MD
                                    Print Title: Trustee







Execution Date:   4-23 , 1999       By: /s/ DAVID B.  THORNBURGH
                                    ----------------------------
                                    Signature and Title
                                    Print Name: David B.  Thornburgh MD
                                    Print Title: Trustee


[Signature Page Second 1998 Financing]







                                   SCHEDULE A





           AZRIEL NAGAR

           EDWARD R. ROLQUIN

           JOSEPH SPANO AND VALERIA SPANO

           DAVID B. THORNBURGH

           DAVID B. THORNBURGH FAMILY TRUST