Professor Massoud Ali-Mohammadi was killed in a bombing outside his home in Tehran on Tuesday.
Iran said on Monday it would take revenge on its arch-foes Israel and the United States for the killing of an Iranian scientist last week, media reported.
Professor Massoud Ali-Mohammadi was killed in a bombing outside his home in Tehran on Tuesday. Officials have accused Israel and the United States of being behind the assassination. Washington has dismissed the charge as absurd.
"The enemies and the Zionist regime (of Israel) should know that ultimately we will give a response to this act," interior minister Mostafa Mohammad-Najjar was quoted as saying by the official IRNA news agency. "Be sure that Iran will take revenge on you for the blood of martyr Massoud Ali-Mohammadi."
Iran's president Mahmoud Ahmadinejad, who often rails against the West, said on Thursday the assassination of the scientist was carried out in a "Zionist style".
Iranian officials have described the slain professor as a nuclear scientist, but a spokesman said he did not work for the Atomic Energy Organisation at the centre of the Islamic Republic's disputed nuclear programme.
"Such a blind act, created by Mossad, the CIA and enemies of the Islamic Republic, shows their weakness," Mohammad-Najjar said.
Last week's bombing occurred at a time of heightened tension in the Islamic state, seven months after a disputed presidential election plunged the country into its most serious domestic turmoil in three decades.
State media described Ali-Mohammadi as a "committed and revolutionary" professor, suggesting he backed the government.
But opposition websites said he was a supporter of opposition leader Mirhossein Mousavi in last June's disputed election, which plunged Iran into turmoil.
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