After intelligence on possible terror attacks led the US to close 21 of its embassies and consulates, Washington issued a worldwide travel alert warning Americans that al Qaeda may be planning attacks in August, particularly in the Middle East and North Africa.
"The Department of State alerts US citizens to the continued potential for terrorist attacks, particularly in the Middle East and North Africa, and possibly occurring in or emanating from the Arabian Peninsula," its statement said.
"Current information suggests that al Qaeda and affiliated organizations continue to plan terrorist attacks both in the region and beyond, and that they may focus efforts to conduct attacks in the period between now and the end of August," it added, saying the travel alert would expire on August 31.
Among the most prominent of al Qaeda's affiliates is Al Qaeda in the Arabian Peninsula, a Yemen-based group whose attempted attacks included the Christmas Day 2009 attempt to blow up a Northwest Airlines flight from Amsterdam to Detroit.
Britain said it would close its embassy in Yemen on Sunday and Monday. "We are particularly concerned about the security situation in the final days of Ramadan and into Eid," Britain's Foreign Office said in a statement, referring to the Muslim holy month which ends on Wednesday.
The US embassies in the following countries have been closed: Afghanistan, Algeria, Bahrain, Bangladesh, Djibouti, Egypt, Iraq, Jordan, Kuwait, Libya, Mauritania, Oman, Qatar, Saudi Arabia, Sudan, the United Arab Emirates and Yemen.
The consulates in Arbil, Iraq; Dhahran and Jeddah, Saudi Arabia; and Dubai, United Arab Emirates will also be shut.
The U.S. Embassy in Tel Aviv, which is normally closed to the public on Sunday, said all its facilities would be shut on Sunday and workers not essential for the building's security had been told not to come in.
It also said the American Center in Jerusalem and the Haifa Consular Agency would be closed on Sunday.