Russia's ambassador to the Unitede Nations Vitaly Churkin died suddenly on Monday in New York.

The 64-year-old had held the post since 2006.

"A prominent Russian diplomat has passed away while at work. We'd like to express our sincere condolences to Vitaly Churkin’s family,” the Russian Ministry of Foreign Affairs said in a statement on its official website.

Agencies reported that Churkin became ill outside the Russian Embassy in New York after suffering heart problems.

He was reportedly rushed to New York Presbyterian Hospital, where he later died.

The announcement his death was met with shock when it was delivered during a session at the UN headquarters.

He is survived by a wife and two adult children. His daughter is believed to be a journalist for the Vladimir Putin-backed Russia Today network.

Churkin was a strident defender of Russian foreign policy, particularly the intensive bombing of Aleppo last year in order to crush rebels opposed to Syrian President Bashar-al-Assad.

Russia's Deputy Permanent Representative to the United Nations Yevgeniy Zagaynov said that Churkin, who was fluent in English, French, Russian and Mongolian, kept working "till the very end”.

Before he was appointed as the country's ambassador at the UN in May 2006, the diplomat served as ambassador to Belgium and Canada, and liaison ambassador to Nato and the Western European Union (WEU).

Russia's Deputy Permanent Representative to the United Nations Yevgeniy Zagaynov said that Mr Churkin, who was fluent in English, French, Russian and Mongolian, kept working "till the very end”.

Before he was appointed as the country's ambassador at the UN in May 2006, the diplomat served as ambassador to Belgium and Canada, and liaison ambassador to Nato and the Western European Union (WEU).

Churkin gained a degree of notoriety in 1986, when as a relatively young diplomat, he testified on the Chernobyl nuclear power station accident, making him the first Soviet official to appear before a Congressional Committee of the US House of Representatives.

Former US ambassador to the UN Samantha Power said that Mr Churkin had been a force for good in US-Russian relations.

She tweeted: "Devastated by passing of Russian UN Amb Vitaly Churkin. Diplomatic maestro &deeply caring man who did all he could to bridge US-RUS differences.”