They said that at least 27 IS fighters were killed the night before when the Shura Council of Jihadis attacked the group in the coastal city, where IS gained its first foothold in Libya last year. Medical officials said 13 Council fighters were killed and 20 wounded.
The Council said in a statement that the push Wednesday night had driven the last IS remnants from the city center. It plans to pursue the remaining IS fighters, who have fled to the nearby mountain suburb of al-Fatayah.
Libya is bitterly divided between an elected parliament and government based in the eastern city of Tobruk, with little power on the ground, and an Islamist militia-backed government in the capital, Tripoli. Hundreds of militias are aligned with either side or battling on their own for power and turf.
Troops loyal to the eastern government and led by Gen. Khalifa Hifter have surrounded Darna for months and until recently appeared to refrain from getting involved in the fighting between the various jihadi militias.
Meanwhile peace talks between some of the warring factions continue. The U.N. Envoy for Libya, Bernardino Leon, has urged the Islamist-backed government in Tripoli to sign a peace deal that would establish a unity government. Members of the Tobruk government and regional leaders signed the unity accord in Morocco earlier this month.