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

An official from the special forces loyal to the internationally-recognized government says 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, former general 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.