LONDON, Jan 5: Britain on Thursday signalled its readiness to use military force if necessary to keep the Strait of Hormuz open, warning Iran not to miscalculate over the West's determination to prevent disruption to the key shipping route.

Iran threatened last week to stop the flow of oil through the Strait of Hormuz if foreign sanctions were imposed on its crude exports over its nuclear ambitions, a move that could trigger military conflict with economies dependent on Gulf oil.

"Alongside the U.S. 5th Fleet in the Gulf, we have naval assets, we have mine counter-measures capability, we have a frigate present there, and we are an integrated part of the allied naval task force in the Gulf and one of the missions of that task force is to ensure that those shipping lanes remain open," British Defence Secretary Philip Hammond told Sky News.

Iran had made similar threats before, but "there should be no miscalculation by the Iranians about the importance that the international community attaches to keeping the Straits of Hormuz open," Hammond said, speaking from Washington where he has gone for talks with his U.S. counterpart Leon Panetta.

Fears of supply disruptions due to rising tensions between the West and Iran have sent oil prices higher.

"Any attempt to close the Straits of Hormuz would be illegal and we need to send a very clear message to Iran that we are determined that the straits should remain open," Hammond said.

Britain's Royal Navy participates in the Combined Maritime Forces, a U.S.-led, Bahrain-based naval flotilla drawn from 25 nations whose missions include counter-piracy, counter-terrorism and security in the Gulf.

The Strait of Hormuz was one of the world's great commercial arteries and its closure would have very significant consequences for the economies of the world, Hammond said.

He said in a speech in Washington earlier that any attempt by Iran to close the strait would fail.

OLIVE BRANCH

At the same time, Hammond held out an olive branch to Iran by urging it to return to negotiations to find a peaceful solution to its nuclear dispute with the West.

The West suspects Iran of seeking to develop a nuclear bomb although Tehran insists its nuclear programme is peaceful.

The last round of talks between Iran and six major powers, including Britain, in Istanbul a year ago, got nowhere. Turkey delivered a Western offer for a resumption to Tehran on Thursday and expressed hope they could restart soon.

Britain shut Iran's embassy in London and expelled all its staff after the British Embassy in Tehran was attacked last November by a crowd angry at British sanctions. Britain also closed its Tehran embassy and evacuated its staff.

Hammond, appointed to the job last October, made his first trip to Washington as defence secretary as President Barack Obama unveiled a new defence strategy in line with Pentagon plans to cut spending after a decade of war.

British troops fought alongside Americans in Iraq and still do so in Afghanistan.

Hammond said there was a "clear view both in the UK and the U.S. and indeed in many other allied countries that we will be seeking to avoid prolonged boots-on-the-ground engagements ... of the type that we had in Iraq and that we currently have in Afghanistan (and) that we should invest more in prevention."

"At the same time, of course, the U.S. has to have an eye on the emerging strength of China as a new major military power," he said.