"The demonstrators, led by a religious figure, seemed to comprise mainly of Islamic extremists. They exploded more than 20 firecrackers in front of the embassy," said one diplomat inside the building.

The protestors were calling for the expulsion of the British ambassador and chanting "death to America, death to Britain", witnesses said.

Riot police were deployed to try to break up the demonstration, the diplomat said.

Earlier in the day, 50 people, the majority of them students at the Marvi theological school, assembled in front of the embassy shouting slogans against the war, and US and British forces battling to oust Iraqi President Saddam Hussein.

The protestors dispersed peacefully after half an hour.

The embassy has been the scene of anti-war demonstrations since US-led coalition began their assault on Iraq on March 20. Hundreds of protesters hurled stones at the embassy on March 28, breaking several windows.

Four days later a car carrying containers of petrol and diesel slammed into the walls of the embassy compound and exploded. The Iranian foreign ministry claimed it was an accident.

Hamid Reza Assefi, a spokesman for the Iranian foreign ministry, said Monday that "appropriate measures" had been taken to prevent a repetition of the incident.

Meanwhile, several thousand theology students and clerics demonstrated in the holy city of Qom to protest against the war on Iraq and the "offence" to the Shiite holy cities of Najaf and Karbala from coalition forces.

"Death to America, death to Great Britain," students who gathered inside Feyzieh theology school chanted.

Najaf and Karbala are the holiest sites in Shiite Islam, after Mecca and Medina, being the burial places of Ali and Hossein, whom Shiites consider the true successors of the prophet Mohamed.

More than 60 percent of Iraqi population and 90 percent of Iranian people are Shitte Muslims.

"We do not support Saddam, we support innocent Iraqi people," said one of the lecturers, loudly applauded by the crowd chanting "Death to Saddam".

Similar demonstrations were organised in seminaries in other cities.

SPACE.WIRE