The Foreign Office says anyone intending "non-essential" travel to the country should postpone their journey until the situation has improved.

The embassies were under siege for a third day on Monday, in protest at Nato's bombing of the Chinese Embassy in Belgrade.

Nato has said the bombing was an accident, caused by faulty intelligence, and has apologised to Beijing.

But British nationals living in China have been advised by the Foreign Office to keep off the streets.

The BBC's Paul Anstiss reports on the anti-Nato demonstrations in China

An advisory note from the FO also says: "If British nationals do intend to travel to China they should not attempt to visit British missions at present but can contact them by telephone.

"British nationals in China should adopt a low-profile and stay off the streets and away from the demonstrations. There is no evidence of any actions against British nationals."

'Keen patriotism'

After whipping up public fury by declaring the Nato strike a deliberate act of war, the Chinese authorities issued a statement intended to limit the violence and soothe jittery foreigners.

Duncan Hewitt in Beijing: "Protesters have been shouting 'down with Clinton, down with Blair'"

Vice President Hu Jintao said in a television broadcast that while he supported the "keen patriotism" of students, demonstrations should not go too far.

He insisted that foreigners, including diplomats and businessmen, were safe.

He said: "We must guard against extreme behaviour and be vigilant against people taking advantage of the opportunity to disrupt normal social order."

It has been suggested that the protests have formed the biggest public protest in Beijing since the Tiananmen Square pro-democracy demonstrations 10 years ago.

A guard stands beside the splattered walls of the British embassy

On Sunday, up to 5,000 angry demonstrators gathered at the British Embassy compound, chanting anti-Nato slogans.

A Foreign Office spokesman said: "There has been some emotional behaviour with the throwing of missiles but the police are out in force and are protecting the building.

"They will prevent anyone breaching the grounds but obviously the ambassador is concerned for his staff."