The closure of the British embassy in Yemen’s capital Sanaa has been extended until the end of the Muslim festival of Eid, the Foreign Office says.
The mission had been set to reopen on Tuesday after a two-day shutdown over fears of a terrorist attack.
But the FCO said “continuing security concerns” meant it would stay shut for the festival, ending later this week.
The US said 19 of its embassies in north Africa and the Middle East would remain closed until Saturday.
US officials met in Washington on Saturday to review the threat of a terrorist attack that led to the Sunday closure of embassies and consulates and a global travel warning to Americans for August.
On its website, the Foreign Office is advising against all travel to Yemen and is strongly urging British nationals to leave.
It says there is “a high threat from terrorism throughout Yemen” and “a very high threat of kidnap from armed tribes, criminals and terrorists”.
A Foreign Office spokeswoman said: “Due to continuing security concerns the British embassy in Yemen will remain closed until the end of Eid.”
Eid marks the end of the Muslim holy month of Ramadan, and UK officials have advised particular vigilance during the festival period, warning that “tensions could be heightened”.
‘Abundance of caution’
Several hundred Britons are thought to live in Yemen, with most working for the embassy, charities, UN organisations and oil companies.
Unlike the US, the UK kept its embassies in Saudi Arabia, Oman, Qatar, Bahrain, Kuwait, United Arab Emirates and Iraq open over the weekend, but advised staff to “exercise extra vigilance”.
It has been suggested that al-Qaeda messages reportedly intercepted by the US were between senior figures talking about a plot against an embassy.
The State Department in Washington said the extended closures of its embassies were “out of an abundance of caution”, and not a reaction to a new threat.
Its diplomatic posts in Abu Dhabi, Amman, Cairo, Riyadh, Dhahran, Jeddah, Doha, Dubai, Kuwait, Manama, Muscat, Sanaa and Tripoli and African missions in Antananarivo, Bujumbura, Djibouti, Khartoum, Kigali and Port Louis will remain closed until Saturday.
US diplomat missions in Algiers, Kabul and Baghdad are among those which will reopen on Monday.