Israeli aircraft have conducted a long-range mission designed to prepare for a possible strike on Iran’s nuclear facilities and to send a message to the world that it is ready to take military action if diplomacy fails to halt Tehran’s atomic programme.

An Israeli political official familiar with the drill, held early this month, said that the Iranians should “read the writing on the wall . . . This was a dress rehearsal, and the Iranians should read the script before they continue with their programme for nuclear weapons. If diplomacy does not yield results, Israel will take military steps to halt Tehran’s production of bomb-grade uranium.”

Mohamed ElBaradei, Director-General of the United Nations nuclear watchdog, the International Atomic Energy Agency, said that he would be forced to leave his position if Iran were attacked. “A military strike, in my opinion, would be worse than anything possible,” he told al-Arabiya television station. “It would turn the region into a fireball.It will mean that Iran, if it is not already making nuclear weapons, will launch a crash course to build nuclear weapons with the blessing of all Iranians, even those in the West.”

Western states suspect Iran of secretly aiming to build a nuclear bomb. Tehran insists that its nuclear facilities are intended to produce electricity.

More than a hundred Israeli F16 and F15 fighter jets took part in manoeuvres over the eastern Mediterranean and Greece to prepare for possible long-range strikes. The central command for the Greek Air Force said yesterday that it had taken part in “joint training exercises” with Israel near Crete.

Reports in the US press said that the aircraft flew more than 900 miles, roughly the distance from Israel to the Natanz nuclear enrichment facility in Iran. “They wanted us to know, they wanted the Europeans to know, and they wanted the Iranians to know . . . There is a lot of signalling going on at different levels,” an unnamed official told The New York Times.

The Israeli military issued a statement saying only that the air force “regularly trains for various missions in order to meet the challenges posed by the threats facing Israel”.

Ehud Olmert, the Israeli Prime Minister, said that he would prefer Iran’s nuclear ambitions to be halted through diplomacy, but he did not rule out military action. “Iran must be stopped by all possible means,” he told an American pro-Israel lobbying group this month.

Israel has regularly consulted the Americans on the Iranian nuclear threat. The issue was high on the agenda during a visit by President Bush to the region in May.

After meeting Mr Bush, the Israeli Prime Minister said: “We reached agreement on the need to take care of the Iranian threat. I left with a lot less question marks regarding the means, the timetable restrictions and America’s resoluteness to deal with the problem.”

The Israelis have kept the Americans abreast of their intelligence, acknowledging that a conflagration between Iran and Israel would probably spread to the rest of the region.

Ahmad Khatami, a hardline cleric, told worshippers at Tehran University yesterday that Israel and the US would receive a “slap in the face” from Iran and its allies if they spoke of using force against them. Iran maintains strong ties with Syria and Hezbollah militants in Lebanon, according to Israeli security experts.

If Israel did neutralise all of Iran’s nuclear abilities, the most damaging retribution would be likely to stem from short to medium-range missiles from Iran, Syria and Lebanon. Iran claims to have Shahab-3 missiles with a range of 1,200 miles, meaning that Israel, US bases in the Gulf and foreign troops in Iraq lie within range.

Though Israel has developed precautions against medium-range missiles, even the most optimistic projections suggest that not all could be intercepted. Lebanese Hezbollah forces used short-range missiles to strike Israel in 2006.

Last month the UN’s International Atomic Energy Agency expressed concern that Iran was hiding details about studies into making nuclear warheads and defying UN demands to suspend uranium enrichment. The UN SecurityCouncil hasimposed sanctions on Iran for defying council demands. Iran has refused to buckle and has spurned offers of economic benefits to suspend uranium enrichment. On Thursday Iran said that it was ready to negotiate over a new package of economic incentives put forward by major powers seeking to persuade Tehran to curb its nuclear work.

Over the past 30 years Israel has twice destroyed suspected nuclear weapons facilities in Middle East states. In 1981 jets raided Osirak, in Iraq, and last September Israeli jets bombed a site in the Syrian desert that the Israeli military believed housed a partly constructed nuclear reactor. The Syrians denied the allegations. Recent rebuilding in the area suggests that no nuclear fallout occurred.

Times Recommends

• Should Knox’s trial even have reached the courtroom?
• 'Was it real?' The US bailout nightmare
• Iranian opposition plays the long game