An Iranian university lecturer and scientist has been killed in a bomb attack in Teheran.
The man, identified by Iranian media as Mostafa Ahmadi Roshan, a chemistry expert and director of the Nantz uranium enrichment programme, was in his car with two other people when the bomb went off.
The explosion was believed to have been caused by a magnetic bomb stuck to the vehicle by a motorcyclist on the campus of Allameh Tabatai University. The two passengers were injured in the attack, Fars added.
Several Iranian nuclear scientists have been assassinated in recent years and Tehran has accused the US and Israel of being behind the deaths. Both countries deny any involvement.
A similar bomb killed Tehran University professor Masoud Ali Mohammadi in January 2010 and in November of the same year, another nuclear scientist, Majid Shahriari, was also killed in Tehran.
The latest assassination comes as tensions intensify between the US, Israel and Iran over Tehran's refusal to halt its nuclear programme.
Iran has now accused Israel of masterminding the attack on Roshan.
"The bomb was a magnetic one and the same as the ones previously used for the assassination of the scientists, and the work of the Zionists [Israelis]," Fars quoted deputy Tehran governor Safarali Baratloo as saying.
Iran recently moved its uranium enrichment programme to the Fordow bunker deep inside a mountain. A warning by Israel's military chief, Lieutenant-General Benny Gantz, that Tehran "should expect more unnatural events in 2012" has added to Iran's suspicions.
"For Iran, 2012 is a critical year in combining the continuation of its nuclearisation, internal changes in the Iranian leadership, continuing and growing pressure from the international community and things which take place in an unnatural manner," Gantz was quoted in local media as saying to a closed-door parliamentary panel in Jerusalem.
A group of Israeli analysts and ex-government officials have warned that Israel would be prepared to strike Iran's nuclear programme facilities even if the country acquires a nuclear weapon.