The U.S. embassy has shut in the Libyan capital Tripoli due to security concerns, the State Department said, according to BBC News.

The embassy staff were evacuated to neighboring Tunisia "due to the ongoing violence resulting from clashes between Libyan militias", it added.

The State Department has also issued a travel warning urging U.S. nationals not to go to Libya. It comes amid fierce clashes between rival militias in the capital, with recent fighting at Tripoli airport.

Libya has been gripped by instability since the 2011 uprising, with swathes of the country controlled by militias.