US diplomatic posts in 19 cities in the Muslim world will be closed at least until the end of this week, the government said, citing "an abundance of caution".

State Department spokeswoman Jen Psaki said the decision to keep the embassies and consulates closed was not an indication of a new threat but "merely an indication of our commitment to exercise caution and take appropriate steps to protect our employees and visitors to our facilities".

Diplomatic buildings will remain closed in Egypt, Jordan, Libya, Yemen, Saudi Arabia and Kuwait, among other countries, until Saturday. The State Department added closures of four African sites, in Madagascar, Burundi, Rwanda and Mauritius but some posts reopened yeterday, including Kabul and Baghdad.

The Obama administration had announced on Friday the embassies would be closed over the weekend and the State Department announced a global travel alert, warning al Qaida or its allies might target either US government or private American interests.

The closure of nearly two dozen US diplomatic posts resulted from the gravest terrorist threat seen in years, the top Republican on the Senate Intelligence Committee said.