Islamic State group jihadists again clashed with fighters from the powerful Fajr Libya militia alliance in the central city of Sirte on Sunday, a local official said.
There were no immediate reports of casualties in the second day of fighting after at least four Fajr Libya fighters were killed on Saturday, according to a source close to the militia alliance.
An AFP correspondent on the western edges of Sirte confirmed that fighting between the two sides had been brief and that calm returned to the city.
Fajr Libya is a coalition of militias, including Islamists, which controls Tripoli where it has installed a government and a parliament opposed to the internationally recognised legislature and cabinet.
On Saturday it fought fierce battles with IS-affiliated jihadists for the first time since February when the extremist militants seized government buildings and the university in Sirte.
The Tripoli-based defence ministry said that several IS fighters were killed on Saturday, without providing a specific toll.
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In a statement posted online, the ministry said Saturday's clashes erupted after IS closed off the coastal road in Sirte in protest at the arrest of jihadist leaders.
In February, Fajr Libya sent reinforcements to Sirte, home town of slain dictator Moamer Kadhafi whose longtime regime was toppled in a 2011 NATO-backed revolt.
Last month was the first time IS jihadists had appeared in the city.
Libya has been plagued by chaos since the end of the 2011 revolt, with heavily armed militias battling for control of its cities and oil wealth and rival governments and parliaments vying for power.
Sirte, 450 kilometres (280 miles) east of Tripoli, has been a bastion of Islamist extremism, with rival groups positioned in the Mediterranean city.
Feeding on the lawlessness that has gripped Libya, IS has extended its influence there from Syria and Iraq where it holds territory on which it has installed a "caliphate".