A remote-controlled bomb has killed a Tehran University professor, according to Iranian state television.
Named as Massoud Mohammadi, authorities say he was a high-ranking nuclear scientist. The academic was apparently killed by a booby-trapped motorbike near his home in the capital.
Iranian media is blaming so-called “counter-revolutionary” elements and Israel.
A neighbour described the blast as very powerful, shattering windows.
Iran is embroiled in a dispute with the West over its nuclear ambitions. It is also in a period of heightened tension, after a disputed presidential election plunged the Islamic Republic into turmoil.