Fighting between government forces and tribal fighters in the southern Libyan town of Kufra has continued for a second day, officials said.
At least 16 people have died since the clashes began on Saturday, with women and children among the dead.
Meanwhile, officials said an election planned for later this month has been postponed to 7 July.
Earlier, a delegation from the International Criminal Court ( ICC) has arrived in Libya to try to secure the release of a four-person team detained after visiting Saif al-Gaddafi, the jailed son of the former leader.
A Libyan official said Australian lawyer Melinda Taylor, who was part of the team, is being investigated on suspicion of spying.
The government said the fighting in Kufra began after members of the Toubou tribe attacked a checkpoint and tried to gain access to a security building nearby and steal their vehicles.
But representatives of the Toubou tribe say they were attacked by security forces - the Deraa brigade - and they have accused the brigade there of trying to "exterminate" them.
Dozens of others were injured in the clashes, while correspondents say the real death toll could be considerably higher.
The BBC's Rana Jawad in Tripoli says much of the fighting is believed to be related to a turf war over smuggling routes used by tribes in the city.
Members of the national army are said to be stationed at the airport in Kufra and are not getting involved, our correspondent adds.