Iran's military warned off a US reconnaissance aircraft trying to approach Iranian naval manouevres, Fars News Agency reported on Tuesday.

The incident involving the two old foes happened on Monday, the semi-official news agency quoted the armed forces chief as saying.

Iran's navy last week launched eight days of exercises in the Gulf and the Gulf of Oman, in a region crucial for global oil supplies.

'A US reconnaissance aircraft which had intended to approach our operational war games left ... upon the timely warning of our air defence forces,' Fars quoted army commander Ataollah Salehi as saying.

He was speaking to reporters as the military test-fired two surface-to-sea missiles in the Gulf of Oman, it added.

There was no immediate US comment on the report.

US Defense Secretary Robert Gates said last week Iran was challenging US naval power in the Middle East with an array of offensive and defensive weapons.

Salehi said: 'It's past the epoch when America would change the regime in a country by just dispatching a warship.'

Iran's latest manoeuvres coincide with rising tension between Iran and the West, which says Tehran's nuclear work is aimed at making bombs. Iran denies this.

The United States is pushing for a fourth round of U.N. sanctions on the Islamic state over its refusal to halt sensitive nuclear activities as demanded by the U.N. Security Council.

Iran often announces advances in its military capabilities and tests weaponry in an apparent attempt to show its readiness for any strikes by Israel or the United States.

Revolutionary guards

In exercises held in the Gulf and the Strait of Hormuz between April 22 and 25, official media said the elite Revolutionary Guards tested missiles and a new speedboat capable of destroying enemy ships.

The Pentagon last month said US military action against Iran remained an option even as Washington pursues diplomacy and sanctions to halt the country's atomic activities.

Israel, widely believed to have the Middle East's only atomic arsenal, has described Iran's nuclear programme as a threat to its existence and has not ruled out military action.

Iran, a predominantly Shi'ite Muslim state, has said it would respond to any attack by targeting US interests in the region and Israel, as well as closing the Strait of Hormuz.

About 40 per cent of the world's traded oil leaves the Gulf region through the strategic narrows.

Salehi said foreign forces had received the message sent by the manoeuvres, saying this was shown by the fact that their war ships kept a distance of about 300-400 km from the drills. He did not specify whether he was referring to US vessels.

Iran was 'very serious about the protection of its interests,' the armed forces chief added. - Reuters