Russia's ambassador to the United Nations, Vitaly Churkin, has died in New York City, the Russian Foreign Ministry said in a statement on February 20.
The statement gave no immediate details but offered condolences to his relatives and said the diplomat had died "unexpectedly" one day before his 65th birthday.
"The Russian Foreign Ministry deeply regrets to announce that Russia's permanent representative to the United Nations, Vitaly Ivanovich Churkin, has died suddenly in New York on February 20, a day ahead of his 65th birthday," it said.
"The outstanding Russian diplomat passed away at his work post," said the statement.
Kremlin spokesman Dmitry Peskov told Interfax that President Vladimir Putin "highly valued the professionalism and diplomatic talent of Vitaly Churkin" and offered condolences to family and colleagues.
Russia's deputy UN ambassador, Vladimir Safronkov, told the AP that Churkin became ill in his office at Russia's UN mission and was taken to Columbia Presbyterian Hospital, where he died February 20. His cause of death wasn't immediately known.
Churkin had served as Russia's envoy to the United Nations since 2006 and was considered Moscow's great champion at the United Nations, where he succeeded Sergei Lavrov -- the current Russian foreign minister.
He had a reputation for an acute wit and sharp repartee especially with his American and Western counterparts.
"He has been such a regular presence here that I am actually quite stunned. Our thoughts go to his family, to his friends and to his government," said Farhan Haq, deputy spokesman for the UN secretary-general's office.
French UN Ambassador Francois Delattre said Churkin was "one of the most talented diplomats" he'd ever met and "an exceptional representative of Russia" at the United Nations.
Churkin was a strong defender of Russian policy, notably its intensive bombing of the Syrian city of Aleppo last year to destroy rebels opposed to President Bashar al-Assad.
Samantha Power, the former U.S. envoy to the United Nations, said she is "devastated" by the death of Churkin, describing him as a "diplomatic maestro" despite their clashes in the UN Security Council on the Syrian conflict.
"Devastated by passing of Russian UN Amb Vitaly Churkin," she wrote on Twitter, adding that he was a "deeply caring man" who tried to bridge differences between the United States and Russia.
When Power accused Syria, Russia, and Iran last year of bearing responsibility for atrocities there, Churkin said she was acting like Mother Theresa and forgetting her own country's track record in the Middle East.
A career diplomat, Churkin was born in Moscow and dabbled in acting in his early teens, notably in two movies about Soviet founding father Vladimir Lenin.
He eventually graduated from the Moscow Institute of International Relations and began work at the Soviet Foreign Ministry, first as a translator before working at the Soviet Embassy in Washington for several years in the 1980s. He also served as Foreign Ministry spokesman from 1990-1992, during the Soviet Union's dying days and afterwards at the Russian Foreign Ministry.
Churkin then served as an ambassador-at-large at the Foreign Ministry, ambassador to Canada, Belgium, and liaison ambassador to NATO.
He was fluent in Russian, Mongolian, French, and English.
Based on reporting by Reuters, AP, AFP, Interfax, and TASS