Libyan gunmen kill 15 soldiers
Gunmen have attacked a military checkpoint south-east of the Libyan capital Tripoli killing 15 soldiers, the authorities say.
A military official said the attack was near Bani Walid, a stronghold in 2011 of supporters of former leader, Muammar Gaddafi.
Several more soldiers were injured in the incident.
It is not clear who carried out the attack, but the government has struggled to control armed groups.
The official, describing it as an ambush, said the attack took place on a road between Bani Walid city and the town of Tarhouna.
The troops came under heavy fire from the gunmen who drove vehicles with mounted machine guns, the official said.
The authorities say four soldiers were injured in the shootings in the Wishtata district.
The main road to Bani Walid was closed while the incident was investigated. It was the single largest known killing of military personnel since the 2011 civil war.
Six soldiers from an elite special forces unit were shot dead in June in the eastern city of Benghazi by masked gunmen. Another six soldiers were killed - also in June - at a checkpoint south of Sirte.
The lack of central government control over large swathes of Libya has left room for armed groups linked to clans and Islamist militants to thrive, analysts say.
Much of the recent violence has been blamed on groups which grew out of the rebel movement behind the overthrow of Col Gaddafi in 2011.
Military officers and other members of the security apparatus are among those to have been targeted in recent weeks.
The lack of security in Libya has also been highlighted this year by clashes in Benghazi as protesters demanded the disbandment of militias.
Gunmen surrounded ministries in Tripoli earlier this year demanding the sacking of officials who worked during Gaddafi's rule.
The army is seen as out-manned and out-gunned by a mix of armed groups seemingly pursuing different agendas, says the BBC's Rana Jawad in Tripoli.
With the surge of attacks of this kind in recent months, many feel there is a sustained campaign to counter the formation of a strong army, our correspondent adds.