The Yemen-based branch of al Qaeda urged Muslims to step up protests and kill more U.S. diplomats in Muslim countries after a U.S.-made film mocking the Prophet Mohammad which it said was another chapter in the "crusader wars" against Islam.

"Whoever comes across America's ambassadors or emissaries should follow the example of Omar al-Mukhtar's descendants (Libyans), who killed the American ambassador," the group said, referring to Tuesday's attack on the U.S. consulate in the Libyan city of Benghazi.

"Let the step of kicking out the embassies be a step towards liberating Muslim countries from the American hegemony," a statement posted on an Al Qaeda in the Arabian Peninsula (AQAP) website on Saturday said.

Fury about the film swept across the Middle East after Friday prayers, with protesters attacking U.S. embassies and in protests that killed at least seven people and prompted Washington to send troops to bolster security at its missions.