MISRATA, Libya (Reuters) - Islamic State militants briefly entered the center of the western Libyan city of Sabratha during overnight clashes with local military brigades before retreating, local authorities said on Wednesday.
Islamist militants have taken advantage of political chaos and a lack of central authority to establish a presence in Libya, with fighters loyal to Islamic State seizing control in Sirte and staging attacks in several other cities.
The fighting in Sabratha started when local brigades - formerly among the many rebel groups that joined in an uprising that overthrew dictator Muammar Gaddafi in 2011 - attacked suspected Islamic State hideouts 15 km (9 miles) south of the city, Sabratha's municipal council said in a statement.
It said the militants then "took advantage of the security vacuum downtown and spread out all over the city" before forced out by the brigades.
Sabratha's mayor said late on Tuesday at least four brigade fighters had been killed and five injured in the clashes.
Local media reported that as many as 17 brigade members were killed, but no officials could be reached to confirm the toll.
A security source from the western city of Zintan said on Wednesday that authorities had agreed to treat the five wounded brigade members from Sabratha, a sign that Zintan and Sabratha may be prepared to cooperate in the fight against Islamic State.
The two cities have been on opposite sides of Libya's post-Gaddafi conflict, with Zintan allied to the internationally recognized government now based in the country's far east and Sabrathan forces among those that support a rival government whose armed supporters seized the capital Tripoli in 2014.
On Friday, the United States carried out an air strike on a suspected Islamic State training camp in Sabratha, killing nearly 50 people. Serbia's government said two Serbian diplomats kidnapped in Libya in November also died in the attack.
(Reporting by Ahmed Elumami; Writing by Aidan Lewis; Editing by Mark Heinrich)