The Russian ambassador to the United Nations, Vitaly Churkin, has died suddenly in New York aged 64, officials said.
Russia’s deputy UN ambassador, Vladimir Safronkov, said that Mr Churkin became ill in his office at Russia’s UN mission and was taken to Columbia Presbyterian Hospital, where he died on Monday.
His cause of death was not immediately known.
Mr Churkin has been Russia’s envoy at the United Nations for a little over a decade 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.
He was previously ambassador at large and earlier served as the foreign ministry spokesman.
Russia’s foreign ministry called Mr 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.
“Our thoughts go to his family, to his friends and to his government,” said UN deputy spokesman Farhan Haq, who heard the news from reporters as it circulated during a daily briefing.
Mr Churkin had a doctorate in history and was a graduate of the Moscow State Institute of International Relations.
Britain’s UN ambassador Matthew Rycroft tweeted that he was “absolutely devastated” to hear of the death of Mr Churkin, “a diplomatic giant and wonderful character”.