The test, believed to have involved a long-range Jericho missile yesterday, came a week after Israeli warplanes practised a long-range bombing mission in Italy - prompting speculation that thecabinet is considering a pre-emptive strike before Iran can complete its first nuclear weapon.

A Whitehall source yesterday said Britain was reviewing its contingency planning for possible military action against Iran. This is thought to include the positioning of British naval ships and ways to keep the Gulf open should Iran retaliate against international oil shipments.

The International Atomic Energy Agency is expected to publish a detailed report next week about Iran's alleged nuclear weapons program.

An Israeli official said Mr Netanyahu was working with Defence Minister Ehud Barak to win support from members of the cabinet who oppose attacking Iranian nuclear facilities, Haaretz newspaper reported.

The report came after days of renewed public discussion among Israeli commentators about the possibility that the Jewish state would take unilateral military action against Iran.

Haaretz said Mr Netanyahu and Mr Barak had already scored a significant win by convincing Foreign Minister Avigdor Lieberman to throw his support behind a strike. But the newspaper cited the Israeli official as saying those opposed to an attack still held "a small advantage" in the cabinet.

Reports said there was opposition from army and intelligence chiefs.

Yesterday's test drew a menacing response from the regime in Tehran. Major-General Hassan Fayrouz Abadi, the chief of staff, was quoted as saying the Islamic Republic would cause "serious damage" to the US and to Israel if it were attacked.

The Israeli media said last week that Mr Netanyahu and Mr Barak favoured a pre-emptive strike on Iran similar to that carried out on Iraq in 1981, when Saddam Hussein's fledgling reactor was bombed by Israeli jets.

Israel did the same to a suspected Syrian reactor in 2007.

Military analysts have warned that for any airstrike to have a chance of halting Iran's nuclear program, which is spread over a number of diverse sites - some built into mountainsides - a large strike force would be needed and heavy losses would be incurred.

There would also be the risk of a long war with Iran and its proxies, Hezbollah in Lebanon and Hamas in Gaza. Both have been provided by Tehran with missiles capable of striking across Israel.

Mr Netanyahu has helped galvanise the West to apply pressure on Iran, but his campaign lost much of its urgency this year when Meir Dagan, the respected outgoing head of the Israeli intelligence agency Mossad, said Iran was not as close to completing a bomb as was generally believed.

This was partly because of the Stuxnet computer virus that disrupted its centrifuges, and which is thought to have been developed by the US and Israel.

Mr Dagan said a military strike on Iran would be a "stupid idea".

The US, which like Israel has declined to rule out military action to prevent Iran developing a nuclear weapons capability, refused to be drawn on the Israeli media reports.

"I'm not going to respond to that kind of speculation," White House spokesman Jay Carney said.

"We remain focused on a diplomatic channel here, a diplomatic course in terms of dealing with Iran."

A poll showed the Israeli government would have support at home for a strike. The Dialog polling institute found 41 cent of 500 surveyed backed such an action while 39 per cent opposed the idea.

Additional reporting: The Times, AP