<P> The OPCW is not an agency of the United Nations, but cooperates both on policy and practical issues . On 7 September 2000 the OPCW and the United Nations signed a co-operation agreement outlining how they were to co-ordinate their activities . Under this agreement, the OPCW reports to the UN General Assembly . </P> <P> The WTO does not have a formal agreement with the UN . Instead, their relationship is governed by exchanges of letters . Unlike the specialized agencies and the IAEA, the WTO has no reporting obligations towards any of the principal organs of the UN, but provides ad - hoc contribution to the work of the General Assembly and ECOSOC . The WTO has a seat on the CEB . </P> <P> The United Nations Chief Executives' Board for Coordination (CEB) brings together on a regular basis the executive heads of the organizations of the United Nations System, under the chairmanship of the Secretary - General of the UN . The CEB aims to further co-ordination and co-operation on a whole range of substantive and management issues facing UN System organizations . In addition to its regular reviews of contemporary political issues and major concerns facing the UN System, the CEB approves policy statements on behalf of the UN System as a whole . Three committees report to the CEB, namely the High - level Committee on Programme (HCLP), the High - level Committee on Management (HCLM) and the United Nations Development Group (UNDG). Each of those bodies has, in turn, developed a subsidiary machinery of regular and ad hoc bodies on the substantive and managerial aspects of inter-agency co-ordination . The committee structure is supported by a CEB secretariat located in New York and Geneva . </P> <P> There is also a Senior Management Group, composed of some of the senior officials in the Secretariat and the funds and programmes at the Under - Secretary - General and Assistant Secretary - General rank, which serves as the cabinet of the Secretary - General . </P>

Which of the following is not one of the principal organs of un