The United States is temporarily removing further staff from its embassy in the Libyan capital, the state department has said, according to BBC News.

It said staff were being withdrawn from Tripoli for security reasons.

The U.S. ambassador to Libya was killed in what the U.S. defense secretary has said was a "terrorist" attack in Benghazi on Sept 11. The attack followed protests triggered by an amateur film made in the U.S. which mocks Islam.

Protests against the film, frequently held on Fridays, have spread across the Muslim world.

A statement on the website of the U.S. embassy in Tripoli warned that demonstrations were possible in both the capital and Benghazi on Friday, Sept 28.

"This is a temporary further drawdown of staff for security reasons," a state department official said in New York. "We will review our posture again early next week with the goal of restoring staff as soon as conditions allow."

It was not revealed how many staff were being withdrawn from Tripoli.