"All four US military personnel being held in Libyan government custody have been released," State Department spokeswoman Jen Psaki said in a brief statement on Friday without elaborating on the cause of their detention.

According to Psaki, the four "were operating in an area near Sabratha as part of security preparedness efforts when they were taken into custody."

Libyan authorities, however, defended their action in arresting the four US military forces, saying their convoy had failed to stop at a checkpoint and were in possession of weapons.

Libyan police and military officials stated that their security forces had stopped three cars at a checkpoint near al-Ajailat in western Libya.

Officers noticed two armed Americans sitting in the first car, Libyan security authorities said, noting that when they asked them about the weapons they were carrying, the other two cars drove away and one caused a traffic accident before police arrived.

The third (American) car, they added, disappeared.

Once their identity had been established, the four detained Americans were sent to Tripoli, local officials said.

RA/MB