Four U.S. military personnel investigating potential evacuation routes in Libya were taken into custody at a checkpoint and detained briefly by the Libyan government before being released, the Associated Press said.

No one was injured. The military personnel were taken to the U.S. Embassy after their release, a U.S. defence department official said.

The four were supporting U.S. Marine security forces protecting the American Embassy, the official said. They were probably U.S. special operations forces, which have been deployed to Libya.

An altercation apparently took place at a checkpoint near the town of Sabratha, the official said. Reports of gunfire could not be confirmed.

After they were detained at the checkpoint, the Americans were transferred to the ministry of the interior and held for a few hours, the official said.

The U.S. Embassy in Tripoli includes a security detail. The embassy's personnel are restricted in their movements in Libya.