The United States is deploying a US Marine anti-terrorism team to Libya to bolster security after a deadly attack on its consulate in Benghazi, a US defense official said Wednesday.

"The Marines are sending a FAST (Fleet Antiterrorism Security Team) team to Libya," the official, who spoke on condition of anonymity, told AFP.

The decision to move the roughly 50-member unit to Libya comes after Washington's ambassador to Tripoli and three other Americans were killed when a mob stormed the US consulate in Benghazi. The crowd had been angered over an amateur American-made film mocking Islam, after video clips from the movie had been posted on the Internet.

The low-budget movie, "Innocence of Muslims," in which actors have strong American accents, portrays Muslims as immoral and gratuitously violent.

President Barack Obama quickly ordered increased security at US diplomatic posts around the world, while slamming Tuesday's deadly assault in Benghazi -- an Islamist stronghold in eastern Libya -- which coincided with the anniversary of the September 11 attacks in the United States.