A force that controls oil terminals in eastern Libya said Monday it has captured the town of Ben Jawad from the Islamic State group, pushing the extremists back along a coastal strip they control east of their stronghold of Sirte.

Spokesman Ali al-Hassi said five Petroleum Facilities Guard fighters have been killed and 18 wounded in fierce clashes in the coastal town, and that fighting is continuing in the nearby town of Nawfiliyah.

A Ben Jawad resident told Reuters that PFG forces had entered the town and were combing the area to secure it. If the PFG can hold Ben Jawad it could prove significant, signaling the start of a new front in the campaign against the Islamic State, also known as ISIS or Daesh.

The PFG has declared its support for Libya's U.N.-backed unity government. Other brigades that back the government advanced last week to the outskirts of Sirte from the west.

"We launched today's attack to purge and liberate the central region from Daesh, and secure this area under the umbrella of the Ministry of Defense and the Presidential Council, the supreme commander of the Libyan army," Hassi said.

Western states hope the unity government, which arrived in Tripoli at the end of March, can resolve Libya's political crisis and bring together armed factions to fight ISIS.

The Islamic State took advantage of the security vacuum in Libya to seize control of Sirte last year, extending its presence along about 155 miles of coastline either side of the central coast city.

In January ISIS announced it had established full control over Ben Jawad, about 100 miles east of Sirte. It also attacked the oil terminals of Es Sider and Ras Lanuf, a little further east, clashing with the PFG and causing extensive damage.

Libya's unity government is designed to replace two rival administrations, backed by loose alliances of armed brigades, that competed for power from Tripoli, in the west, and from eastern Libya. But the new government has struggled to win support in the east, where it is still seeking formal backing from the internationally recognized parliament.

Khalifa Haftar, the commander of forces loyal to the eastern government, has so far rejected the Presidential Council and has announced a separate campaign to capture Sirte. His forces have been mobilizing close to PFG-controlled territory, but have not so far moved decisively toward the west.

The PFG is a paramilitary force of several thousand men that was set up to protect oil installations in eastern Libya but has acted independently and been split by internal divisions.

The main PFG commander, Ibrahim Jathran, was previously aligned with eastern factions, before switching his allegiance. Jathran has said he is willing to work with the unity government and reopen oil terminals that the PFG has long blockaded.