The International Atomic Energy Agency (IAEA) chief, Yukiya Amano, passed away at the age of 72, the agency announced on Monday.
"The Secretariat of the International Atomic Energy Agency regrets to inform with deepest sadness of the passing away of Director General Yukiya Amano," the agency said in a statement.
It said the IAEA flag will be lowered to half-mast.
Amano was Japan's Resident Representative to the Agency from 2005 until his election as director general in July 2009. He assumed his duties as IAEA Director General on Dec. 1, 2009.
EU foreign policy chief Federica Mogherini expressed grief over the demise of Amano.
"A man of extraordinary dedication & professionalism, always at the service of the global community in the most impartial way. I’ll never forget the work done together. It has been for me a great pleasure & privilege working with him," she wrote in a Twitter message.
By Diyar Guldogan