British diplomats leave Iran.

Britain has evacuated all its diplomatic staff from Iran, Western diplomatic sources told Reuters on Wednesday, a day after protesters stormed and ransacked its embassy and residential compound.

Both properties were severely damaged, with official and personal possessions seized or destroyed, said sources who had spoken to staff at the embassy. One described the damage as "carnage".

Britain said it was outraged by the attacks and warned of "serious consequences".

"In light of yesterday's events, and to ensure their ongoing safety, some staff are leaving Tehran," Britain's foreign office (ministry) said in a statement.

While the official statement referred only to "some staff", two diplomatic sources said that all British staff were leaving.

The two embassy compounds were stormed mid-afternoon on Tuesday during a demonstration in the street outside the main building in downtown Tehran, smashing windows, torching a car and burning the British flag in protest against new sanctions imposed by London.

Protesters broke into the residential compound at Qolhak in north Tehran, a sprawling, wooded property which used to be the embassy's summer quarters.

Iranian media said there were between 100 and 300 protesters in Qolhak and some 50 in the main, downtown compound. The storming lasted for a matter of hours and appeared to be over by mid-evening after local police intervened.

An Iranian report said six British embassy staff had been briefly held by the protesters and then freed by police, something British Foreign Secretary William Hague played down, saying the situation had been "confusing" and he would not have called them "hostages".

Several sources told Reuters that diplomats had had their movements restricted by protesters and one said staff in the main compound had been herded into a room while protesters ransacked the compound.