Libya's fledgling armed forces are struggling to curb militias who fought in the uprising against Muammar Gaddafi but refuse to disarm and control parts of the country.

Gunfire and explosions could be heard in Benghazi and thick smoke rose from the Ras Obeida area. The army ordered residents to stay off the city streets and recalled troops on leave to their units in the city.

Fighting broke out when an army special forces unit pursued a suspect into an area where militant group Ansar al-Sharia operates its own checkpoints, Benghazi city security officials said.

Ansar al-Sharia was blamed for the attack on the US consulate in Benghazi a year ago when the US ambassador and three other Americans were killed.

The chaos in Libya is worrying its neighbors.

Rival militia groups withdrew from Tripoli last week after clashes killed more than 40 people when protesters marched to one of the militia bases to demand they leave the capital city.

Hoping to co-opt former fighters, the government hired militia groups to provide security. But they remain loyal to their commanders or tribes, and often clash in disputes over territory or personal feuds.

RA/NJF