A senior Iranian official on Sunday blamed the United States and Israel for the killing of an Iranian scientist, who the deputy interior minister said was not linked to Iran's nuclear programme as reported by media.

Darioush Rezaie, 35, a university lecturer, was shot dead by gunmen in eastern Tehran on Saturday. Some media reports said Rezaie was a nuclear scientist but Deputy Interior Minister Safarali Baratlou said this was not true.

Parliament Speaker Ali Larijani in a speech broadcast live on state TV blamed the United States and Israel for the killing.

"The terrorist action by American and the Zionist regime (Israel) yesterday ... is another example of the level of their  animosity (against Iran)," he said. Iranian media said security officials were investigating the killing.

Several nuclear scientists have been assassinated in Iran in the last few years. One scientist was killed and another wounded in Tehran in November, which Iranian officials blamed Israel and the US for. Washington dismissed that at the time.

It has not been officially confirmed whether Rezaie was involved in Iran's nuclear programme, as reported by some media. Lawmaker Zohreh Elahian said Rezaie had no links to Iran's nuclear programme, which the United States and its allies say is a cover to build bombs.     
"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 Elahian, the semi-official Fars news agency reported.

Tehran governor Morteza Tamaddon warned that Iran "preserves the right to retaliate", the semi-official Mehr news agency reported. Tamaddon did not elaborate. - Reuters