Assailants on motorcycles attached magnetized bombs to the cars of two nuclear scientists as they were driving to work in Tehran on Monday, killing one and wounding the other, Iranian officials said. The president accused Israel and the West of being behind the attacks.
Iran's nuclear chief, Ali Akbar Salehi, said the man killed was involved in a major project with the country's nuclear agency, though he did not give specifics. Some Iranian media reported that the wounded scientist was a laser expert at Iran's Defense Ministry and one of the country's few top specialists in nuclear isotope separation.
Iranian officials said they suspected the assassination was part of a covert campaign aimed at damaging the country's nuclear program, which the United States and its allies says is intended to build a weapon - a claim Tehran denies. At least two other Iranian nuclear scientists have been killed in recent years, one of them in an attack similar to Monday's.
President Mahmoud Ahmadinejad told a press conference that "undoubtedly, the hand of the Zionist regime and Western governments is involved in the assassination."
But he said the attack would not hamper the nuclear program and vowed that one day Iran would take retribution. "The day in the near future when time will come for taking them into account, their file will be very thick," he said.
Asked about the Iranian accusations, Israeli government spokesman Mark Regev said Israel did not comment on such matters. Washington has strongly denied any link to previous attacks.
The attacks, as described by Iranian officials, appeared sophisticated.