During his tenure as Permanent Representative, Chowdhury served as President of the Security Council, President of the United Nations Children's Fund (UNICEF) Executive Board and Vice-President of the Economic and Social Council of the UN in 1997 and 1998. He had served for more than 10 years as the Coordinator for the Least Developed Countries in New York City. In May 2001, he led the negotiations on behalf of the least developed countries at the Third United Nations Conference on Least Developed Countries, which adopted the comprehensive Brussels Programme of Action for the present decade.