The US state department issues a worldwide travel alert related to an al-Qaeda threat and advises Americans to take extra care when they are abroad.
The state department said the potential for terrorism is particularly strong in the Middle East and north Africa, with the possibility that an attack could occur or come from the Arabian Peninsula.
A state department statement said: Current information suggests that al-Qaeda and affiliated organisations 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.”
American travellers are urged to take extra precautions when they are travelling overseas, sign up for state department alerts and register with US consulates in the countries they are visiting.
The alert is related to the earlier decision to close US embassies and consulates throughout the Muslim world on Sunday after an unspecified threat was made.
This threat is also linked to al-Qaeda and is focused on the Middle East and Central Asia, according to Ed Royce, chairman of the House of Representaitves foreign affairs committee.
State department officials said on Thursday that they were taking action out of an “abundance of caution”.
Spokeswoman Marie Harf said there were indications of a threat to US facilities overseas and some diplomatic facilities may stay closed for more than a day.
Other US officials said the threat was in the Muslim world, where Sunday is a work day.
Congressman Royce said: “We’ve had a series of threats. In this instance, we can take a step to better protect our personnel and, out of an abundance of caution, we should.” He refused to say if the National Security Agency’s surveillance programme had helped reveal the threat.
Friday’s alert says al-Qaeda or its allies could attack US government or private American interests, with public transport and tourist sites possible targets.
The statement says: “US citizens should take every precaution to be aware of their surroundings and to adopt appropriate safety measures to protect themselves when traveling.”
The state department issued a major warning in 2012 informing American diplomatic facilities across the Muslim world about potential violence connected to the anniversary of the 11 September terrorist attacks.
Dozens of American installations were besieged by protests over an anti-Islam video made by an American.
In Benghazi, Libya, the US ambassador and three other Americans were killed when militants attacked a diplomatic post. The attack was not related to the demonstrations.