Story highlights Law enforcement official: Churkin died after suffering from cardiac arrest in New York

Former US ambassador: Churkin was "a formidable adversary, but always a friend"

(CNN) Tributes poured in for Vitaly Churkin, the Russian ambassador to the United Nations who died suddenly Monday in New York.

Churkin died one day before his 65th birthday. He was known as a deeply intelligent, combative, disarming and humorous fixture at the UN Security Council.

The diplomat suffered from cardiac arrest while at the Russian Mission on East 67th Street, a law enforcement official said. He was taken to New York-Presbyterian Hospital, where he died.

Preliminary information suggests there was no foul play in Churkin's death, New York police Lt. Thomas Antonetti said. But authorities are waiting for reports from the New York City medical examiner's office before releasing the official cause of death.

The Russian Foreign Ministry said, "The outstanding Russian diplomat died while he was in his current working role." And President Vladimir Putin "expressed sympathy to the friends and family as well as to the staff of the Russian Foreign Ministry," the Kremlin said.

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