Iranian nuclear scientist Massoud Ali Mohammadi was killed on Tuesday in a rare bomb attack in Tehran which state media quickly blamed on Iran's arch-foes the United States and Israel.
Mohammadi, a lecturer at Tehran university, died when a bomb strapped to a motorcycle was triggered by remote control outside his home in the northern Tehran neighbourhood of Qeytariyeh, state media said.
He was "assassinated" on Tuesday morning by "a bomb which US and Zionist agents had already placed near his house," state television said without naming any sources.
Tehran prosecutor Abbas Jafari Dolatabadi told the ISNA news agency that Mohammadi was a lecturer in nuclear energy and said a booby-trapped bike parked outside his house exploded as he was getting into his car.
"The judiciary has launched an investigation ... No suspects have yet been arrested," he said.
Bomb attacks are rare in Iran although several security officials and members of the elite Revolutionary Guards have been killed in bombings by rebels in restive Sistan-Baluchestan province in the east of the country.
A witness said that today's explosion was a "strong blast breaking windows in neighbouring houses and cars."
Iran's state-run Arabic-language television Al-Alam identified Mohammadi as a "hezbollahi" teacher -- a term used for staunch supporters of the Iranian regime.