Britons have been urged to leave Yemen immediately amid fears of escalating violence.

The Foreign Office has warned against all travel to the Middle Eastern country and said any Britons who stay in Yemen are unlikely to be able to be evacuated if unrest worsens.

The British embassy in the capital Sana'a is to shut from tomorrow for two days.

The Foreign Office warning states: "The Foreign and Commonwealth Office advise against all travel to Yemen and strongly urge British nationals to leave now. If you don't leave the country now while commercial carriers are still flying it is extremely unlikely that the British Government will be able to evacuate you or provide consular assistance."

The US has issued a global travel alert based on an unspecified al Qaeda threat. All of the country's embassies will shut tomorrow around the Muslim world. However, British embassies in Saudi Arabia, Oman, Qatar, Bahrain, Kuwait, the UAE and Iraq will stay open amid heightened vigilance for staff.