The Director General of the International Atomic Energy Agency (IAEA), Yukiya Amano, died aged 73, AP reported.
Amano, a former Japanese diplomat, had experience in disarmament and non-proliferation diplomacy, as well as nuclear energy issues, and had been the IAEA chief since 2009.
The diplomat also served in the United Nations (UN), since 1972 he held various posts in the Ministry of Foreign Affairs of Japan.