U.S. Rep. Ed Royce, R-Calif., who heads the House Foreign Affairs Committee, told CNN the closings begin Sunday.
"It's my understanding that it is al-Qaida-linked, all right, and the threat emanates in the Middle East and in Central Asia," Royce said.
A U.S. official told CNN Thursday the State Department had learned of a "credible and serious" threat. The department on Twitter has said the embassies in Egypt, Saudi Arabia, Iraq and Kuwait are to be closed Sunday and possibly for some days thereafter.
Another official said the embassy in Yemen was likely to be in danger. President Obama met Thursday with Yemeni President Abdo Rabu Mansour Hadi.