The Revolutionary Guards land forces fought back the hypothetical air strike from enemy helicopters, planes and missiles with 620 anti-aircraft cannon and shoulder missiles, state television said.

“Today, we are fighting back at all kinds of planes at low and average altitudes,” said Brigader General Mohammad Reza Zahedi, the commander of the Guards’ land forces.

“The manoeuvre is exceptional in terms of the number and types of the weapons used. We have used anti-helicopter weapons with a range of more than 10 kilometres (six miles),” he said.

It was the second of the three-day “Power Manoeuvre” exercises involving 3,000 units of the elite force in 16 of Iran’s 30 provinces, the second war games staged by the Guards this month.

Although Washington has always said it wants to solve the standoff over Iran’s controversial nuclear programme through diplomacy, it has never ruled out the option of military action against Iran to halt the atomic drive.

The exercises came as aircraft carrier USS John C. Stennis and its accompanying strike group joined the USS Dwight D. Eisenhower in the Sea of Oman on Tuesday, in a move widely interpreted as a warning to to Tehran.

The Stennis “entered the US 5th Fleet area of operations... to conduct maritime security operations in regional waters, as well as to provide support for ground forces operating in Afghanistan and Iraq,” the US Fifth Fleet said from its base in Manama.

“We are ready, we are sustainable, we are flexible and we provide significant capabilities that contribute to regional peace and security,” said the strike group’s commander Rear Admiral Kevin Quinn.

The strike group, to which 6,500 sailors and marines have been assigned, also includes the guided-missile cruiser USS Antietam, guided-missile destroyers USS O’Kane and USS Preble, and fast combat-support ship USNS Bridge.

Tensions between Washington and Teheran over the Iranian nuclear programme are spiralling, with Iran set to ignore the latest UN deadline for it to suspend sensitive uranium enrichment activities.

“We are not planning for a war with Iran,” US Defence Secretary Robert Gates said earlier this month when asked about the deployment of the second aircraft carrier group to the region’s waters.

“The purpose of that (deployment) is simply to underscore to our friends, as well as to our potential adversaries in the region, that the United States has considered the Persian Gulf and that whole area and stability in that area to be a vital American national interest,” he said.

The United States accuses Iran of seeking a nuclear weapon, a charge denied by Tehran which insists its atomic programme is solely aimed at generating energy.

Washington has also alleged that elements in Iran have smuggled sophisticated bombs into Iraq have killed at least 170 US and allied soldiers since June 2004. Tehran has rejected the allegations as ”without foundation”.

The Revolutionary Guards’ war games opened on Monday with a flurry of missile test-firing which commanders said was aimed at strengthening the defensive capabilities of the force.

The IRNA agency said a total of 750 missiles and cannon munitions would be fired during the exercises, being staged less than two weeks after similar manoeuvres by the Guards’ air force and naval units.