UNITED NATIONS - 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.

Also on Monday, former UN secretary-general Ban Ki-moon said in a statement issued in Seoul, capital of South Korea, that he was "shocked and truly saddened" to learn of the passing of Churkin.

"During my 10 years as secretary-general, it was a privilege to work with him and watch him represent the Russian Federation with such passion and dedication. He was an outstanding diplomat and an intellectual star," said Ban, who was succeeded by Guterres on Jan. 1 after his two five-year terms as the UN chief.

"His diplomatic skills, quick wit, and ready sense of humor will long be remembered by those who knew him and by those who will study the history of the United Nations in the years to come," said Ban, adding that he extended his "deepest condolences" to the Russian government and, in particular, to Churkin's wife Irina and the rest of his family.

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

Churkin has been Russian permanent representative since 2006, who succumbed after an apparent heart attack in New York on the eve of 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.