A/RES/51/231 Page 4 Committee on Administrative and Budgetary Questions to the General Assembly at its fifty-second session; 19. Endorses the concern of the Advisory Committee on Administrative and Budgetary Questions about the use of suppliers recommended by requisitioners, notes that this practice undermines the principle of segregation of responsibilities between requisitioning and procurement entities, and requests the Secretary-General to discontinue the practice; 20. Requests the Secretary-General to ensure that in no case will a consultant who has been engaged to prepare specifications and to assist in technical evaluation be allowed to recommend vendors for invitations to bid; 21. Also requests the Secretary-General to redouble his efforts to streamline all aspects of the decision-making process in procurement at Headquarters; 22. Notes that the local committees on contracts have the authority to consider cases ranging from 50,000 dollars to 200,000 dollars, while the Headquarters Committee on Contracts will consider cases in amounts above 200,000 dollars; 23. Takes note of the information supplied in paragraphs 93 and 94 of the report of the Board of Auditors,12 indicating that 48 per cent of suppliers were from one Member State; 24. Invites Member States to encourage their national suppliers to be registered in the supplier roster; 25. Requests the Secretary-General to expedite the steps being taken to establish a supplier roster on as wide a geographical basis as possible and to submit a report thereon, including a revised list of suppliers, through the Advisory Committee on Administrative and Budgetary Questions to the General Assembly at its fifty-second session; 26. Emphasizes that concerted efforts should be made to identify potential vendors in the developing countries and countries with economies in transition and to increase the representation from those countries in the bidding for and award of contracts, so as to develop a supplier base that is more representative of the membership of the Organization; 27. Takes note of paragraph 13 of the report of the Advisory Committee on Administrative and Budgetary Questions,10 and decides to revert to this question during its consideration of the proposed programme budget for the biennium 1998-1999; 28. Requests the Secretary-General to take immediate action to ensure compliance with the established procedures for procurement, based on international competitive bidding and the widest possible geographical base of procurement; 29. Appreciates the efforts being made to address the problem of ex post facto cases, in particular for those offices away from Headquarters, and requests the Secretary-General to ensure that the approval of contracts on an ex post facto basis is kept to the minimum, with full justification for each such case; 12 Official Records of the General Assembly, Fifty-first Session, Supplement No. 5 (A/51/5), vol. I, sect. II. /...