Heavy fighting flared up in Libya's second-largest city, Benghazi, on Sunday as forces loyal to the internationally recognized elected government try to retake areas controlled by extremist militias.

An official from the special forces loyal to the elected government said the ongoing operation in multiple areas started early Saturday.

The official, speaking on condition of anonymity because he was not authorized to speak to journalists, said the air force is backing up the ground troops.

On Oct. 15, retired Gen. Khalifa Hifter and the elected government joined ranks against Islamist militias controlling Benghazi.

Since then they have managed to take control of most of the city.

The widespread militia violence has plunged Libya into chaos less than four years after a NATO-backed uprising toppled and killed longtime dictator Moammar Gadhafi.