Iranian media claim Israel behind car bomb death of scientist

Meanwhile, Japan joined the sanctions effort, pledging to buy less Iranian oil, a day after China reacted coolly to the US effort.

Japan gets 10% of its oil from Iran but Jun Azumi, the finance minister, says his country will halt those imports. He met Timothy Geithner, the US treasury secretary yesterday.

Iran's claim that Israel or the US was behind the bombing that killed a 32-year-old nuclear scientist in Tehran this week might be accurate and part of a covert campaign to stop the Islamic republic from pursuing nuclear weapons, The New York Times reported yesterday.

The paper said that current and former American officials, and experts on Iran believe the campaign is being carried out mainly by Israel.

Mostafa Ahmadi Roshan, who was a department supervisor at the Natanz uranium enrichment plant, was killed on Wednesday when a magnetic bomb attached to his car exploded. He was at least the fifth Iranian scientist with nuclear connections to be killed since 2007. The blast also killed Roshan's driver/bodyguard and wounded a third occupant of the Peugeot 405.

Iranian officials immediately blamed both Israel and the United States for the bombing.

Iran's ambassador to the United Nations, Mohammad Khazaee, sent a letter of protest to the UN secretary general Ban Ki-moon, blaming "certain foreign quarters" for what he called "terrorist acts" aimed at disrupting Iran's "peaceful nuclear programme, under the false assumption that diplomacy alone would not be enough for that purpose".

Patrick Clawson, the director of the Iran Security Initiative at the Washington Institute for Near East Policy, told The Times that "sabotage and assassination is the way to go, if you can do it". "It doesn't provoke a nationalist reaction in Iran, which could strengthen the regime. And it allows Iran to climb down if it decides the cost of pursuing a nuclear weapon is too high."

A former senior Israeli security official, said the uncertainty about who was responsible was useful. "It's not enough to guess," he said. "You can't prove it, so you can't retaliate. When it's very, very clear who's behind an attack, the world behaves differently."

Yesterday a hard-line Iranian newspaper called for retaliation against Israel.

The Kayhan newspaper chief editor, Hossein Shariatmadari, wrote: "Assassinations of Israeli military and officials are easily possible.".

Protests in Iran over the bombing called for yesterday in front of the French, German and British embassies were cancelled because of lack of authorisation, Iran's Fars news agency reported. It added they would be now be held sometime after today's funeral for Roshan.

The British Embassy in Tehran has been closed since demonstrators angry at western sanctions ransacked it at the end of November last year. The US and Israel do not have diplomatic ties with Iran.

Both the White House and the US State Department denied involvement in the attack that killed Roshan.

"The United States had absolutely nothing to do with this," said Tommy Vietor, a spokesman for the National Security Council. The US secretary of state, Hillary Rodham Clinton, on Wednesday denied "any United States involvement in any kind of act of violence inside Iran".

"We believe that there has to be an understanding between Iran, its neighbours and the international community that finds a way forward for it to end its provocative behaviour, end its search for nuclear weapons and rejoin the international community," Mrs Clinton said.

An Israeli military spokesman, Brig Gen Yoav Mordechai wrote on Facebook: "I don't know who took revenge on the Iranian scientist, but I am definitely not shedding a tear".

Israeli media highlighted comments by Israel's military chief of staff, Lieut Gen Benny Gantz, saying the day before the attack that 2012 would be a critical year for Iran, in part because of "things which happen to them [the Iranians] in an unnatural way".

The Times reported that, according to its sources, the CIA has repeatedly tried to derail Iran's uranium enrichment programme by covert means, including introducing sabotaged parts into Iran's supply chain.

The US is conducting an international lobbying effort to win support for new sanctions against Iran, targeting its oil industry, which would bar financial institutions from the US market if they do business with Iran's central bank.

Japan joined the sanctions effort yesterday, pledging to buy less Iranian oil, a day after China reacted coolly to the US effort.

Iran's "nuclear development problem can't be ignored by the world, so from that perspective we understand the US actions", Japan's finance minister, Jun Azumi, said after meeting with the US treasury secretary, Timothy Geithner.

Japan imports about 10 per cent of its oil from Iran, Mr Azumi said.

"We plan to start reducing this 10 per cent share as soon as possible in a planned manner," he said.

Turkey, which imports oil and gas from Iran, however, said it was only bound by UN sanctions against Iran, despite the US campaign to sanction Iran further over its nuclear programme. The foreign ministry spokesman, Selcuk Unal, said yesterday that Turkey would evaluate the content of the US sanctions but it "does not feel it is bound by any other sanctions".

The Russian Security Council secretary, Nikolai Patrushev, warned in an interview published by the daily Kommersant yesterday that military escalation over Iran was likely and that "Israel is pushing the Americans towards it".

"There is a real danger of a US military strike on Iran," he said.

* With additional reporting by the Associated Press, Reuters and Agence France-Presse