Military chiefs have told the United States that they are ready and able to destroy Iran's nuclear weapons facilities - with an attack as early as March.

The revelation comes as Iran faces growing isolation over its decision to restart its uranium enrichment programme in defiance of the International Atomic Energy Authority (IAEA).

The UN-backed authority has warned that the country could be just three years away from building a nuclear weapon after it broke UN monitors' seals at its Natanz plant on Tuesday to restart work on its nuclear programme.

Iran's hardline president Mahmoud A hmadinejad, announced: "Iran is not frightened by threats from any country and it will continue the path of production of the nuclear energy. Iranian people do not allow foreigners to block their progress."

The decision, which sparked alarm across the Middle East and western powers, follows an earlier call by President Ahmadinejad for Israel to be "wiped off the map".

He has also suggested that the Jewish state be moved to Europe and denies that the Holocaust ever happened.

Britain, France and Germany last week called for an emergency session of the IAEA to refer Iran to the UN Security Council with the implied threat of sanctions as international fears grow that Iran's "civilian" nuclear programme conceals an ambitious secret effort to build atomic bombs.

Condoleezza Rice, the US secretary of state, backed the move, accusing Iran of a "provocative" and "deliberate escalation" w hile, in a surprise development, Russia signalled that it would also give its support.

It is thought unlikely, however, that China, a permanent member of the UN security council, will bow to diplomatic pressure and join calls for sanctions against Iran for breaching its international nuclear obligations.

Israeli military chiefs say their plans to strike Iran's nuclear sites are "feasible", say intelligence sources.

They claim the Israelis are certain that an attack by their military machine would be as effective in destroying the Iranian project as it was against the Iraqi Ossiraq nuclear site in 1981. An Israeli missile attack would be expected to set back Iran's nuclear weapons programme by up to 10 years. The new government of acting Israeli Prime Minister Ehud Olmert also wants President Ahmadinejad to understand that the incapacitation of Ariel Sharon, following his stroke, would not affect Israel's state of military readiness.

A recent statement by the Israeli military chief of intelligence, General Aharon ZeeviFarkash, indicated that Israel had set a March 1 time limit for diplomatic means to deter Iran's plans. Sources in Tel Aviv say the general's remarks were based on a military planning timetable and could indicate a likely date for the missile strike. General Dan Halutz, Israel's chief of staff, said last week that there were several military means to deal with the problem.

He ordered a report as part of strategic cooperation talks with the United States and it was discussed recently when senior Israeli military figures met the heads of several US intelligence agencies.

President George W Bush's administration has attempted to quell any serious discussion of an attack following homegrown intelligence assessments that claimed the administration could wait until at least 2008 before Iran emerged as a nuclear threat.

Israel's military brass has concluded, however, that an Israeli or US strike on Iran could eliminate that nation's nuclear weapons facilities.

Israeli air force fighter pilots have been training for the past 10 years to survive antiaircraft and radar threats from Soviet antiaircraft systems which have been sold to Iran and other Middle Eastern states.

The Israelis have also received help from former Soviet or Russian anti-aircraft officers who emigrated to Israel.

The Israeli air force also chose recently to reveal details of its cooperation with Iran's neighbour Turkey, including the deployment of Israeli fighter jets there and Turkish squadrons in Israel as part of a joint training programme.

Earlier this month, President Ahmadinejad publicly called for Islam to prepare to "rule the world".

He said Islam did not restrict itself to national borders, saying: "We must believe in the fact that Islam is not confined to geographical borders, ethnic groups and nations. It's a universal ideology that leads the world to justice."

He added: "We don't shy away from declaring that Islam is ready to rule the world."