Article published on the 2010-01-12 Latest update 2010-01-12 10:45 TU
Mohammadi, a lecturer at Tehran University, died when a bomb strapped to a motorcycle was triggered by remote control in the northern Tehran neighbourhood of Qeytariyeh.
Iran's state broadcaster said Mohammadi was "assassinated in a terrorist act by counter-revolutionaries and agents of the arrogance".
Iranian officials usually refer to the United States and some other Western powers as the"global arrogance."
Tehran prosecutor Abbas Jafari Dolatabadi told the ISNA news agency that Mohammadi was a lecturer in nuclear energy and said the booby-trapped bike was parked outside his house and 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 eastern Iran.
None of the reports said whether Mohammadi was connected to Iran's controversial nuclear programme, which the West suspects is masking an atomic weapons programme.
Iran has been under international pressure to halt its sensitive uranium enrichment programme which is at the centre of fears about Iran's ambitions as the process which makes nuclear fuel can also be used to make atom bombs.
Despite three rounds of UN Security Council sanctions, Iran has continued to expand its nuclear programme.