[ http://www.who.int/governance/eb/who_constitution_en.pdf ]
(e) to provide or assist in providing, upon the request of the United Nations, health services and facilities to special groups, such as the peoples of trust territories;
Territories or groups of territories which are not responsible for the conduct of their international relations may be admitted as Associate Members by the Health Assembly upon application made on behalf of such territory or group of territories by the Member or other authority having responsibility for their international relations. Representatives of Associate Members to the Health Assembly should be qualified by their technical competence in the field of health and should be chosen from the native population. The nature and extent of the rights and obligations of Associate Members shall be determined by the Health Assembly.
(h) to invite any organization, international or national, governmental or non-governmental, which has responsibilities related to those of the Organization, to appoint representatives to participate, without right of vote, in its meetings or in those of the committees and conferences convened under its authority, on conditions prescribed by the Health Assembly; but in the case of national organizations, invitations shall be issued only with the consent of the Government concerned;
Regional committees shall be composed of representatives of the Member States and Associate Members in the region concerned. Territories or groups of territories within the region, which are not responsible for the conduct of their international relations and which are not Associate Members, shall have the right to be represented and to participate in regional committees. The nature and extent of the rights and obligations of these territories or groups of territories in regional committees shall be determined by the Health Assembly in consultation with the Member or other authority having responsibility for the international relations of these territories and with the Member States in the region.
[ http://www.who.int/governance/rules_of_procedure_of_the_wha_en.pdf ]
The Director-General may invite States having made application for membership, territories on whose behalf application for associate membership has been made, and States which have signed but not accepted the Constitution to send observers to sessions of the Health Assembly.
PLENARY MEETINGS OF THE HEALTH ASSEMBLY
Plenary meetings of the Health Assembly will, unless the Health Assembly decides otherwise, be open to attendance by all delegates, alternates and advisers appointed by Members, in accordance with Articles 10-12
inclusive of the Constitution, by representatives of Associate Members appointed in accordance with Article 8 of the Constitution, and the resolution governing the status of Associate Members, by representatives of the Board, by observers of invited non-Member States and territories on whose behalf application for associate membership has been made, and also by invited representatives of the United Nations and of other participating intergovernmental and non-governmental organizations admitted into relationship with the Organization.
PARTICIPATION OF REPRESENTATIVES OF ASSOCIATE MEMBERS AND OF INTERGOVERNMENTAL AND NON-GOVERNMENTAL ORGANIZATIONS AND OF OBSERVERS OF NON-MEMBER STATES AND TERRITORIES
Representatives of Associate Members may participate equally with Members in meetings of the Health Assembly and of its main committees except that they shall not hold office nor shall they have the right to vote. They may participate equally with Members in other committees, subcommittees or other subdivisions of the Health Assembly except the General Committee and the Committee on Credentials.
Observers of invited non-Member States and territories on whose behalf application for associate membership has been made may attend any open meetings of the Health Assembly or any of its main committees. They may, upon the invitation of the President, and with the consent of the Health Assembly or committee, make a statement on the subject under discussion.Such observers shall have access to non-confidential documents and to such other documents as the DirectorGeneral may see fit to make available. They may submit memoranda to the Director-General, who shall determine the nature and scope of their circulation.