Gevork Vartanian, a former Soviet intelligence agent who helped derail a Nazi plot to assassinate allied leaders during World War Two, has died. He was 87 years old.

Russia's Foreign Intelligence Service made the announcement Wednesday, saying Vartanian died Tuesday in Moscow.

Vartanian, whose father was a Soviet agent of Armenian descent based in Iran, began working for Soviet intelligence at the age of 16. In 1943, he participated in foiling a Nazi plot to assassinate Soviet leader Josef Stalin, U.S. President Franklin D. Roosevelt and British Prime Minister Winston Churchill when they held a conference in the Iranian capital, Tehran.

He had earlier obtained information about graduates of a British intelligence school in Tehran who were sent to the Soviet Union, allowing Soviet authorities to catch them.

Russian President Dmitry Medvedev sent his condolences to Vartanian's widow, praising him as a legendary and brilliant personality who became a part of the country's history.