The UN General Assembly has mourned the sudden death of Russian Ambassador to the UN Vitaly Churkin.

Ahead of a General Assembly meeting held here on Monday, diplomats rose and stood in a moment of silence to pay a tribute to Churkin, Xinhua news agency reported.

Churkin, who has been the Russian permanent representative to the United Nations since 2006, died of an apparent heart attack in New York on Monday morning at the age of 64, just a day before his 65th birthday.

General Assembly President Peter Thomson said that the assembly is shocked and deeply saddened by the passing of Churkin, while expressing the heartfelt condolences to Churkin’s family as well as staff at the Russian mission to the UN.

Thomson spoke highly of Churkin’s “great intellect,” sense of humor and his considerations for others.

“We’ve all experienced and respected the pride that he took in serving his country and the passion at times of very stern resolution that he brought to his job,” said Thomson.

“Not only has Russia lost one of its truest sons, here at the United Nations, we’ve lost one of our truest,” he added.

The General Assembly will hold a formal meeting to pay a tribute in memory of the late Russian Ambassador Churkin at an appropriate time, according to Thomson.

“The Russian Foreign Ministry is saddened to announce the death of Vitaly Churkin, Russia’s Permanent Representative to the UN, on Monday in New York, a day before his 65th birthday,” said a brief statement, without disclosing the cause of his death.

The ministry expressed its condolences and hailed Churkin as an “outstanding diplomat,” who has served as Russian envoy to the UN since 2006.