Russia's ambassador to the United Nations, Vitaly Churkin, died suddenly on 20th Feb 2017 after falling ill in his office at the mission, Russian officials said.
Churkin, 64, was rushed to NewYork-Presbyterian/Columbia University Medical Center in New York, where he died.
His cause of death wasn't immediately known.
Churkin had been Russia's envoy at the United Nations since 2006 and was considered Moscow's great champion at the UN
He had a reputation for an acute wit and sharp repartee, especially with his American and Western counterparts.
Russia's foreign ministry called Churkin an "outstanding" diplomat and expressed condolences to his friends and family.
His death, the day before his 65th birthday, stunned officials at the UN's headquarters.
Churkin was previously ambassador at large and earlier served as the foreign ministry spokesman. He had a doctorate in history and was a graduate of the Moscow State Institute of International Relations.