LONDON — Iran said on Tuesday that it had executed a man accused of being an Israeli intelligence agent responsible for the assassination of one of its nuclear scientists, Iranian state media reported.

Press TV, a satellite broadcaster, identified the man as Majid Jamali Fashi and said he had been convicted of killing the scientist, Masoud Ali Mohammadi, in January 2010. Mr. Mohammadi was a 50-year-old professor at Tehran University whose role in Tehran’s nuclear program was unclear. At the time of his death, Iran’s Atomic Energy Organization said he had no role in the nuclear program.

The case seemed to be part of a shadow war played out between Iran and Israel, which has shown growing impatience with Western efforts to employ diplomacy and sanctions in the enduring crisis over Tehran’s nuclear program. Iran says the program is for peaceful purposes, but Western leaders suspect that Tehran is seeking the capability to build a weapon.

At the time of Mr. Mohammadi’s killing, state media in Iran reported that a remote-controlled bomb attached to a motorcycle went off outside his home in north Tehran. Iran blamed the United States and Israel for the attack. A State Department spokesman in Washington dismissed the accusation of United States involvement as “absurd.”

Press TV said Mr. Fashi had been executed at Tehran’s Evin prison. He had also been found guilty of “receiving training from Mossad” — the Israeli spy agency — inside Israel and of being given $120,000 to assassinate the Iranian scientist. He had also confessed to using forged documents, received in Azerbaijan, to travel to Tel Aviv, the broadcaster said.

The Iranian state news agency accused Mr. Fashi of traveling abroad “on several occasions” to be trained.

The killing was one of several apparently aimed at Iranians associated with nuclear research. The latest came in January when Mostafa Ahmadi Roshan, 32, who was deputy director of the Natanz uranium enrichment plant, was killed on his way to work in rush-hour traffic in Tehran.

While Israel generally declines comment on such assassinations, Iran routinely blames Israeli agents for seeking to derail its nuclear program.

Iranian news accounts said that a motorcyclist slapped a magnetized bomb on Mr. Roshan’s car, killing him and mortally wounding his driver and bodyguard, identified as Reza Qashaqei.

The execution of Mr. Fashi came weeks after Iran’s state media announced that 15 people, including Iranians and unspecified foreigners, had been arrested in connection with what the country’s Intelligence Ministry described as a “Zionist-regime-linked” plot to assassinate one of its “specialists.”

The report by the state broadcaster IRIB also said Iran’s intelligence services had uncovered an Israeli spy base in a neighboring country, without elaborating.

The execution also coincided with talks in Vienna between Iranian envoys and officials from the International Atomic Energy Agency to discuss the agency’s desire to inspect facilities that it suspects have been used to test explosives capable of detonating a nuclear charge, which Iran denies.

The talks, set to continue Tuesday, however, are also seen as an informal precursor to talks scheduled this month in Baghdad, between Iran, the United States and other nations.