The United States extended embassy closures by a week in the Middle East and Africa as a precaution on Sunday, Aug 4, after an al Qaeda threat that U.S. lawmakers said was the most serious in years, according to Reuters.

The State Department said 19 U.S. embassies and consulates would be closed through Saturday "out of an abundance of caution" and that a number of them would have been closed anyway for most of the week due to the Eid celebration at the end of the Muslim holy month of Ramadan.

The United States initially closed 21 U.S. diplomatic posts for the day on Sunday. Some of those will reopen on Monday, including Kabul, Baghdad and Algiers.

Four new diplomatic posts - in Madagascar, Burundi, Rwanda and Mauritius - were added to the closure list for the week.

Last week, the State Department issued a worldwide travel alert warning Americans that al Qaeda may be planning attacks in August, particularly in the Middle East and North Africa.

U.S. military forces in the Middle East region have been on a higher state of alert for the past several days because of the threat. The threat also has prompted some European countries to close their embassies in Yemen, home to an al Qaeda affiliate that is considered one of the most dangerous: al Qaeda in the Arabian Peninsula.

Yemeni soldiers blocked roads around the U.S. and British embassies in Sanaa, while troops with automatic rifles stood outside the French Embassy.

Interpol, the France-based international police agency, on Saturday issued a global security alert advising member states to increase vigilance against attacks after a series of prison breaks in Iraq, Libya and Pakistan.