Troops commanded by Libyan military strongman Khalifa Haftar announced the recapture Tuesday of two key oil installations, as fighting raged in Tripoli where a rival government has struggled to assert its authority.
Libya has experienced years of violence and lawlessness since the 2011 NATO-backed ouster of longtime dictator Moamer Kadhafi, with rival parliaments and governments trading barbs and militias fighting over territory and the country's vast oil wealth.
Forces loyal to Haftar mounted a day-long assault by land, sea and air to retake the oil export terminals of Ras Lanuf and Al-Sidra, after both sites were seized by a rival, Islamist-led force earlier this month.
"The armed forces... have liberated the whole of the oil crescent," said Ahmed al-Mesmari, a spokesman for pro-Haftar forces.
He said 10 fighters of Haftar's forces were killed and that rival fighters of the Benghazi Defence Brigades (BDB) were being chased back to their barracks.
The head of the oil installation guards, General Meftah al-Megaryef, also said the two terminals had been recaptured.
Basset al-Shairi, a commander of the BDB which had seized the two sites on March 3, said Ras Lanuf had fallen, but without specifying the outcome in nearby Al-Sidra.
In September, pro-Haftar forces had already captured the terminals and two other eastern oil ports in a blow to the authority of the UN-backed unity government in Tripoli.
Haftar backs a rival administration in the country's far east that has refused to cede power to the Government of National Accord (GNA) working in the capital since last year.
Oil accounts for more than 95 percent of Libya's revenues.
Haftar's forces, which call themselves the Libyan National Army (LNA), have battled jihadists in second city Benghazi for more than two years.
- Tanks 'under our balcony' -
In Tripoli, fresh fighting raged on Tuesday between rival armed groups, authorities in the capital said, causing UN Libya envoy Martin Kobler to call for an "immediate ceasefire".
"Civilians at grave risk in ongoing clashes," he wrote on Twitter.
Gunfire and explosions could be heard in two neighbourhoods west of the city centre, witnesses said, and several key thoroughfares were blocked, leaving many trapped in their homes.
Witnesses said tanks had deployed in the neighbourhoods of Hay al-Andalus and Gargaresh, after the fighting broke out late Monday.
"Early this morning, several tanks and vehicles equipped with anti-aircraft weapons passed under our balcony," Abdel-Nur Bachir, a retired 80-year-old businessman living in Gargaresh, told AFP.
It was not immediately clear who was involved in the clashes.
The Tripoli police, who are loyal to the GNA, said they were "purging" the area of "outlaws", but did not announce any casualties.
A resident of Hay Al-Andalus, who spoke on condition of anonymity, said she was trapped indoors.
"We have nowhere to go to escape the fighting. All we can do is pray that no shelling hits the house," she said.
"People are holed up indoors. Schools are closed."
- 'Complex' ties -
Since Kadhafi's fall, several armed groups have battled for control of the capital in the absence of a regular army or police force.
The GNA has denied having any connection to the takeover of Ras Lanuf and Al-Sidra earlier this month.
A Libya expert, in a briefing released last week, described the relationship between the GNA -- and the Presidential Council (PC) that heads it -- and the BDB that led the attack on the oil terminals as "complex and somewhat unclear".
"While the GNA's Minister of Defence, Mahdi al-Barghati, supports the group, as do some members of the PC, the PC has officially condemned the attack and stated it had no ties to the BDB," Claudia Gazzini of the International Crisis Group think-tank said.
The BDB were formed in 2016 by fighters including Islamists ousted from Benghazi by Haftar's forces.
The GNA said last week that it had ordered oil installation guards who are loyal to it to secure the two terminals.
Last month, Haftar and GNA head Fayez al-Sarraj agreed to form a committee to explore amending the UN-backed agreement that gave rise to the unity government.
But the pro-Haftar eastern parliament, which was elected in 2014, last week suspended its participation in political dialogue and called for presidential and legislative elections to be held before next February.