UNITED NATIONS, Feb. 20 (Xinhua) -- UN Secretary-General Antonio Guterres said Monday that he "learned with shock and sadness" the news of the sudden death of Vitaly Churkin, Russia's permanent representative to the United Nations.

"Ambassador Churkin was a uniquely skilled diplomat, a powerful orator with great wit, and a man of many talents and interests," said Guterres in a statement issued Monday night.

"Although we served together for a short time, I greatly appreciated the opportunity to work with him and will deeply miss his insights, skills and friendship."

Guterres paid tribute to Churkin's contributions to the United Nations and offered condolences to his family, and to the Russian government and people.

Describing the late Russian ambassador as an outstanding diplomat, the secretary-general noted that Churkin served his country "with distinction through some of the most challenging and momentous periods of recent history."

For more than a decade, Churkin was "a forceful presence on the Security Council," said the statement.

Peter Thomson, president of the UN General Assembly, and the UN Security Council respectively issued statements to mourn Churkin's death.

Churkin died of an apparent heart attack in New York on Monday morning at the age of 64, just a day before his 65th birthday.

Born on Feb. 21, 1952 in Moscow, Churkin served as ambassador-at-large at the Russian Foreign Ministry from 2003 to 2006, before his appointment as ambassador to the United Nations. He was Russian ambassador to Canada from 1998 to 2003, and to Belgium from 1994 to 1998.