Forces loyal to Libya’s eastern government said they staged an air strike against opponents in the central Jufra region on Monday. Ahmed al-Mismari, a spokesman for the eastern-based Libyan National Army (LNA), said the strike had targeted a camp used by the Benghazi Defense Brigades (BDB), a force that the LNA has previously clashed with.

Led by Field Marshall Khalifa Haftar the LNA over the last few months has made substantial military gains in Benghazi and Libya’s Oil Crescent region, provoking several attempted counter-attacks by rivals.

“This was a pre-emptive strike against militias that are mobilizing for an attack against the Libyan army,” Mismari said. There was no immediate comment from the BDB.

Images from the oasis town of Houn posted on local media sites showed thick smoke rising close to residential buildings. No casualties were reported.

The LNA carried out air strikes this month to repel what it said was an attempt to recapture Oil Crescent ports it took control of in September. Shortly afterwards, it launched strikes against opponents at a military base in Jufra.

The strikes have raised fears of a new escalation in Libya’s conflict. A U.N.-backed government in Tripoli has so far failed to reconcile Libya’s warring factions.