U.S. President George W. Bush has given Israel an "amber light" to begin preparations for a military attack on Iran, a Pentagon official told The Sunday Times this week.

"Amber means get on with your preparations, stand by for immediate attack and tell us when you're ready," the official said.

The official told the Times that Bush informed the Israeli government he would back an Israeli plan to strike Iran's main nuclear sites with long-range aerial weapons if diplomatic talks over Tehran's contentious atomic program broke down.

Bush's voice of support comes despite U.S. military officials' opposition to the risks of an aerial strike on Iran, the official told The Times. However, the U.S. would not deploy American forces for such a strike nor would Israel be able to depend on U.S. military bases in Iraq for logistical support, the official said.

The U.S. would not necessarily give the "green" light for an attack without unquestionable proof that Iran is involved in military preparations of its own, the official told The Times.

Iran last week test launched a series of medium-range ballistic missiles it claimed were capable of striking Israel. The tests were seen as provocative and prompted Israel to showcase its Eitam plane, released last year, which it said is capable of spying on Iran.

An image surfaced in all the major media outlets on the day Iran announced its first round of test launches, depicting four missiles being fired simultaneously.

However, the AFP and the Associated Press subsequently retracted the photo and replaced it with an image containing only three missiles. After being shown the photograph by AFP, Mark Fitzpatrick of the London-based International Institute for Strategic Studies said "it very much does appear that Iran doctored the photo to cover up what apparently was a misfiring of one of the missiles."

Ahmadinejad: Iran will 'cut hands' off anyone who tries to attack

Iran's president said that even before its enemies "get their hands on the trigger" the country's military would cut them off, media said on Sunday, in an escalating war of words that has stoked Middle East tension.

The comments by President Mahmoud Ahmadinejad came a day after a senior Iranian official said Iran would strike Israel and U.S. bases in the region if the Islamic Republic was attacked over its disputed nuclear program.

"Before the enemies get their hands on the trigger the armed forces will cut off their hands," the official IRNA news agency quoted Ahmadinejad as telling reporters.

Israel, long assumed to have its own atomic arsenal, has sworn to prevent Iran from emerging as a nuclear-armed power.

Last month Israel staged an air force exercise that stoked speculation about a possible assault on Iranian nuclear sites.

Iran has vowed to strike back at Tel Aviv, as well as U.S. interests and shipping, if it is attacked, asserting that missiles fired during wargames last week included ones that could hit Israel and U.S. bases in the region.

Ahmadinejad said the weaponry displayed in the Revolutionary Guards' missile exercise, which was condemned by Western powers, was only a small part of Iran's defense capability.

"In the event of necessity, additional parts of our defence capability will be put on display for the world to see," the president said.