"In an optional decision from the Foreign and Commonwealth Office (FCO), eight women and children whom neither were officials left Iran, with no specific date of return, until the current threats subside," a British diplomat told AFP.

"We have also asked the non-essential visa operators to take the chance and leave, but we have no plans to send diplomats home," he added.

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.

The diplomat advised all British nationals in Iran to remain "extra vigilant".

"Nonetheless, and despite the threats, our embassy will remain open in Tehran, working in full capacity," he said.

Unlike the US, which cuts its diplomatic ties with Iran in 1980, British has enjoyed warmer relations with Iran in recent years.

SPACE.WIRE