USA - After years of professing their parents' innocence, Julius and Ethel Rosenberg's sons acknowledge their father was a spy.

After years of professing their parents' innocence, Julius and Ethel Rosenberg's sons acknowledge their father was a spy. Rosenbergs were executed in 1953 for turning over atomic secrets to Soviet Union. Rosenbergs' sons still have doubts that mother was spy. The about-face came after their father's co-defendant, Morton Sobell, admitted for the 1st time that he and Julius Rosenberg stole nonatomic military and industrial secrets for the Soviet Union. The Rosenbergs were executed in 1953 for passing atomic secrets to the Soviet Union. Since then, decoded Soviet cables have appeared to confirm that Julius was a spy, but doubts have remained about Ethel's involvement. The 91-year-old Sobell, who was convicted with the Rosenbergs on espionage charges in 1951 and released from prison in 1969, had maintained his innocence until last week, when he told The New York Times he turned over military secrets to the Soviets during World War II. "I don't have any reason to doubt Morty," the Rosenbergs' son Michael Meeropol told the Times in Wednesday's editions. Michael was 10 years old when his parents were executed. His brother, Robert, was 6. As adults, they sued the government for documents relating to their parents' case and worked to establish their innocence. In separate interviews with the Times since Sobell's confession, the brothers said they concluded they could no longer claim their father was innocent of an espionage conspiracy. They still say, however, that any atomic bomb information he gave the Russians was at best superfluous, that the case against their parents was flawed and that neither deserved the death penalty. Along with Sobell and others, both brothers still have doubts about the government's case against their mother. Sobell told the Times last week he believes Ethel Rosenberg was aware of espionage by her husband but didn't actively participate.