Fresh fighting between Toubou tribesmen and the national army flared in the Libyan desert town of Kufra overnight leaving up to 12 people dead and scores wounded, local sources told AFP on Saturday.
"Twelve people have been killed and more than 35 have been wounded" since Friday, Toubou tribal leader Issa Abdelmajid Mansur said.
He said his toll drew on reports from two Toubou residential areas.
"They are firing at us with rocket-propelled grenades, Grad rockets and anti-aircraft guns," said Mansur, accusing the national army of ethnic cleansing in the southeastern town.
Mansur said two Toubou neighbourhoods were attacked throughout Saturday by forces linked to the national army, including the Libya Shield brigade, and the military council of Kufra.
Another tribal elder echoed him.
"The attacks on Toubou areas started at 2 pm yesterday (Friday) and have continued past 7 pm today," he said, adding that at least four Toubou tribesmen were killed in his neighbourhood alone.
"A dozen houses have been burned down," he added.
That toll and account of the violence matched one provided by a nurse treating Toubou wounded in a makeshift clinic.
"Four people were killed and 16 wounded," the nurse said, adding that there was sporadic fire and that "several houses have been burned down."
Toubou tribal elders accused army leaders of being unable to rein in their men.
"The army is unable to stop the Libya Shield brigade which is meant to be under its command," Hussein Sake told AFP.
He said he was among Toubou tribal elders who took part in negotiations with the national army aimed at ending the bloodshed.
"Until now, we haven't reached a ceasefire," Sake said, adding that the humanitarian situation was pitiful since Toubou areas have no clinics and no food shops were open because of the violence.
Several officials contacted in Tripoli said they were aware of the fighting in Kufra but were hazy on the details.
On Friday, Wissam Ben Hamid, head of the Libya Shield brigade, said that fighting erupted after Zwai tribesman shot dead a Toubou man.
"The Toubou reacted by firing on every car passing near their neighbourhood," Hamid told AFP, adding three of his men were wounded.
"We asked them to pull back in vain," he said.
On Saturday, Colonel Fradj Bushaala, a local representative of the defence ministry, told AFP that fighting had abated and that "negotiations were under way between tribal leaders to settle the problem once and for all."
Bushaala said some of his men had been wounded but there were no fatalities in their ranks.
"The problem started because the Toubou opened fire on the army and wounded some of their men," said one Kufra resident.
In February, clashes pitting Toubou against Zwai tribesmen in Kufra cost more than 100 lives also displaced half the population, according to UN figures.
Libya's nascent army intervened by sending a brigade of former rebel fighters from the eastern city of Benghazi to uphold a hard-won ceasefire.
Kufra, a town of about 40,000, is located in a triangle where the borders of Egypt, Chad and Sudan meet.
The Toubou, who are dark-skinned and present in southeast Libya as well as in Chad, Sudan and Niger, faced discrimination under toppled Libyan leader Moamer Kadhafi's regime.