CAIRO (AP) — Libyan authorities on Sunday said they have found 18 bodies buried in a mass grave in a former stronghold of the Islamic State group along the conflict-stricken North African nation's coast.

The Missing Persons Authority said in a statement the bodies were unearthed in the Sabaa area of Sirte, a city in central Libya. The bodies were taken to a local hospital, it added.

Sirte, the birthplace of former longtime dictator Moammar Gadhafi, fell under the control of Islamic State militants between 2015 and 2016. The militants, along with al-Qaida, gained a foothold in oil-rich Libya amid the chaos that engulfed the country after the 2011 uprising and a NATO intervention in the conflict.

The militants were eventually driven out of the city in December 2016 by Libyan forces supported by the U.S. and allied with the U.N.-backed government in the capital Tripoli. Hundreds of alleged former Islamic State fighters remain incarcerated in Libyan prisons, many of whom are awaiting trial.

Since Ghadafi's overthrow and killing, Libya has been split between rival authorities. Sirte is now controlled by forces loyal to military leader Khalifa Hifter based in the country's east.

In its statement, the Missing Persons Authority said they collected samples of the dead bones in an effort to identify the bodies. Further details on the cause of death for those found were not provided.

Several mass graves have been uncovered across Libya recently. In October, officials said they found 42 bodies in a mass grave in a school site in Sirte.

In December 2018, the bodies of more than thirty men were discovered near Sirte, believed to be the corpses of a group of Ethiopian Christians whom Islamic State fighters executed in a video the group published years earlier.

In the western town of Tarhuna, hundreds of corpses have been uncovered across several graves after militia fighters loyal to Hifter retreated from the area in June 2020.