Ali Larijani, Iran's parliamentary speaker on Sunday blamed the United States and Israel for the killing of an Iranian scientist reports Reuters.

Larijani told the Parliament that Saturday's attack was another example of American-Zionist animosity against Iran, in a speech broadcast live on the Fars news agency.

Darioush Rezaie, 35, a university lecturer was shot down by two unknown assailants while he and his wife were on their way to their daughter's kindergarten class on Saturday. His wife was also attacked and was hospitalized.

Some media organisations had reported that Rezaie was a nuclear scientist but Deputy Interior Minister Safarali Baratlou said this is not true.

Rezaie was an elite Iranian physicist ... he was murdered by our country's enemies. But ... he didn't have any connection to Iran's nuclear activities, said lawmaker Zohreh Elahian, the semi-official Fars news agency reported.

Security officials are investigating Rezaie's assassination. Iran's ties with U.S. and Israel seem to be fraying as Iran blamed these two countries for the death of a nuclear scientist in November.

According to the report, several nuclear scientists have been assassinated in Iran in the last few years. In January 2010, Iranian physicist Massoud Ali-Mahmoudi was killed in a bomb attack outside his Tehran home.

Even though Iran claims that its nuclear programs are only for civilian purposes, it has refused to stop its uranium enrichment activities as demanded by the United Nations Security Council added the report.