IRAN'S diplomats were flown out of Britain yesterday after being expelled by the UK Government in response to protesters storming its embassy in Tehran, toughening a confrontation between Tehran and the West over its nuclear programme.

Foreign Secretary William Hague announced on Wednesday that Britain was closing its embassy in Tehran, a day after protesters entered two British diplomatic compounds there, smashing windows, torching a car and burning the Union flag in protest against new sanctions imposed by London.

The Iranian diplomats slipped away as the green, white and red Iranian flag continued to fly over the Iranian embassy in west London, the scene of a six-day siege in 1980 when gunmen seized 21 hostages, two of whom they killed.

A Foreign Office spokesman confirmed that yesterday afternoon "all diplomatic staff of the Iranian Embassy in London took off from Heathrow airport".

Across the street from the embassy, a dozen protesters opposed to Iran's government chanted "Free Iran" and urged "terrorists" to go home. A few police officers stood guard.

Many demonstrators were members of the London Green Movement, which opposes President Mahmoud Ahmadinejad and campaigns on Iranian human rights issues.

Akbar Karimiam, 49, said: "As an Iranian, I'm embarrassed about what happened in the British embassy in Tehran.

"The Iranian embassy here is not representing the nation, it's representing the regime. We are here to say goodbye to the dictator regime represented here."

Meanhwhile, at Tehran University, crowds chanted "death to Britain" during Friday prayers as hardline cleric Ahmad Khatami warned the United Nations and the EU were siding with London.

Mr Khatami said the UN Security Council was as bad as the UK, which Iranian radicals feel is plotting to bring down their Islamic system.

"Issuing a statement against Iran means falling into a well with the rotten rope of Britain," Mr Khatami said to chants of "Death to Britain".

This week's spat exacerbates a stand-off between Iran and the West over Iran's nuclear programme at a time when there has been renewed speculation that Israel or the United States could launch military strikes against Iran's nuclear infrastructure.

Western powers suspect Iran is seeking to develop nuclear weapons, but Iran insists its programme is peaceful.

Britain's Ambassador to Iran, Dominick Chilcott, said hardliners in the Iranian establishment may have thought confrontation would rally Iranians to their cause, but miscalculated how strong Britain's response would be.

"They probably didn't expect us to send home the Iranian embassy in London and, reading between the lines, you can see in the way they have responded to that move, some remorse in having provoked it," he said.

He claimed the ruling regime was likely to have supported an attack on the UK embassy in Tehran.

Iran said it regretted the incident, which it described as "unacceptable behaviour by a small number of protesters".

However, Mr Chilcott said: "Iran is not the sort of country where spontaneously a demonstration congregates and then attacks a foreign embassy.

"That sort of activity is only done with the acquiescence and the support of the state."

France, Germany and the Netherlands recalled their ambassadors from Tehran for consultations as a protest against the storming of the British embassy compounds and the European Union moved swiftly to ratchet up sanctions.