Tehran: An Iranian nuclear scientist was killed on Wednesday in a Tehran car bomb assassination blamed on Israel that threatens to ignite a dangerously tense international standoff over Iran's atomic programme.

An Iranian official immediately blamed "the Zionist regime" for the explosion, saying the method -- two men on a motorbike attaching a magnetic bomb to the target's vehicle -- was similar to those used in the assassinations of three other scientists over the past two years.

Iran's parliament erupted with yells of "Death to Israel" and "Death to America" during a speech by one MP who said Wednesday's attack would not dissuade the Islamic republic from "achieving progress."

Mostafa Ahmadi Roshan, 32, died immediately in Wednesday's blast, which occurred in front of a university campus in east Tehran.

Two other occupants of the Peugeot 405, one of them his bodyguard/driver, were wounded, Iranian media reported.

Ahmadi Roshan was a deputy director at Iran's Natanz uranium enrichment facility, according to the website of the university he graduated from a decade ago, Sharif University.

He was specialised in making polymeric membranes to separate gas. Iran uses a gas separation method to enrich its uranium.

"The responsibility of this explosion falls on the Zionist regime," the deputy governor of Tehran province, Safar Ali Bratloo, told Iran's Arabic-language Al-Alam broadcaster, using Iran's term for Israel.

"The method of this terrorist action is similar to previous actions that targeted Iran's nuclear scientists," he said.

Three other Iranian scientists were killed in 2010 and 2011 when their cars blew up in similar circumstances. At least two of the scientists had also been working on nuclear activities.

One of the attacks occurred exactly two years earlier, on January 11, 2010, killing scientist Masoud Ali Mohammadi. The current head of Iran's atomic organisation, Fereydoun Abbasi, escaped another such attempt in November 2010, getting out of his car with his wife just before the attached bomb exploded.

Those attacks were viewed by Iranian officials as assassination operations carried out by Israel's Mossad intelligence service, possibly with help from US counterparts.

Wednesday's killing sharpened an international confrontation over Iran's nuclear programme in which threats and counter-threats are being increasingly backed with militarized displays of muscle.

Western nations, the United States in the fore, are steadily ratcheting up sanctions on Iran with the aim of fracturing its oil-dependent economy.

Iran has responded by saying it could easily close the Strait of Hormuz -- a chokepoint for 20 percent of the world's oil at the entrance to the Gulf -- if it is attacked or the sanctions halt its petroleum exports.

It has also threatened to unleash the "full force" of its navy should the United States redeploy an aircraft carrier to the Gulf, where the US Fifth Fleet is based.

(Agencies)