MOSCOW, JULY 27 -- The Soviet Union announced today that it had carried out the death sentence against Fyodor Fedorenko, a 79-year-old former Nazi concentration camp guard who in 1984 was the first U.S. citizen to be deported here on war crimes charges.

Fedorenko, a Ukrainian who as a young Red Army recruit surrendered to the occupying Nazis in 1941, was convicted of treason and mass murder after an emotional trial in Simferopol in the Crimea in June 1986.

According to 21 volumes of evidence compiled by Soviet prosecutors, Fedorenko served as a member of the Nazi SS at the notorious concentration camp in Treblinka in Poland, where he personally took part in executions, herding prisoners to their deaths in gas chambers, according to the official Soviet news agency Tass said.

Tass did not say when Fedorenko was executed.

Fedorenko emigrated to the United States from Germany in 1949, and was employed as a factory worker in Connecticut. He became a U.S. citizen in 1970 and was deported to the Soviet Union in 1984 after losing a seven-year legal battle.

Earlier this year, another accused Nazi war criminal, 67-year-old Karl Linnas, who had lived in the United States for 36 years, was deported to the Soviet Union to stand trial for crimes committed at a death camps in Tartu, in the Baltic republic of Estonia.

Linnas died July 2 of heart and kidney disease in a Leningrad hospital. He had been convicted and sentenced to death in absentia in 1962.

Tass said Fedorenko was one of 150 names provided by the Soviet procurator's office to the United States over the last 10 years. Tass did not say how many were wanted for war crimes.

At his trial in Simferopol last year, Fedorenko said he had joined the Nazis because he was preoccupied with saving his life. But in the announcement of his conviction, Tass said he had pleaded guilty to the charges.