The Foreign office has warned of threats from terrorism in the region

The Foreign Office confirmed on Tuesday the measure had been in place since 10 February.

Meanwhile UK officials have warned terrorists may be in the final stages of planning an attack in Saudi Arabia.

The new warning came after a British Airways flight to Riyadh, due to fly on Monday, was cancelled amid security fears.

A Foreign Office spokeswoman said it was not known how long the Damascus embassy would remain closed to the public.

We believe that terrorists remain determined to carry out further attacks in Saudi Arabia, and that these may be in the final stages of preparation Foreign Office

She said such decisions were taken according to changing threat levels, and kept constantly under review.

Current Foreign Office travel advice for Syria says there is a high threat to Western interests from terrorism, as in other places in the Middle East, and urges vigilance in public places.

The government has issued fresh guidance to travellers about the possibility of an imminent attack in Saudi Arabia.

Officials warn of "a continuing high threat of terrorism" and advise Britons "against all but essential travel" to the kingdom.

'Situation stable'

It goes on to urge British nationals to keep a "low profile" and to "maintain a high level of vigilance, particularly in public places frequented by foreigners such as hotels, restaurants and shopping malls".

The charge d'affaires at the Saudi Embassy in London, Abdullah Al-Shahrood, said Saudi Arabia "had nothing to do" with the cancellation of Monday's BA flight.

"We have British MPs visiting Saudi Arabia these days and the situation is stable," he told BBC Radio 4's Today programme.

"Good intelligence we are getting will improve the situation but terrorism is an international problem. We have to have the co-operation of the international community so that we can destroy it," he said.

A similar warning to the latest one was issued by the Foreign Office at the end of December.

Accommodation in Riyadh, housing diplomats from the Arab world and their families, was attacked by suicide bombers on 8 November.

That attack left 18 dead as well as 120 wounded, many of them children.

And co-ordinated suicide attacks on Western diplomatic compounds in Riyadh on 12 May last year left 34 dead, including the two Britons and the nine bombers.