A Libyan diplomat on Friday, warned of a escalating violence in the coastal town of Sirte and said a battle between ISIS and local militias has left between 150 and 200 dead.

"A real massacre is taking place, and we call on the international community to intervene," said Libyan ambassador to France, Chibani Abuhamoud, to news agency AFP.

An official on the Sirte council said earlier that the fighting erupted Tuesday as authorities in the militia-held capital Tripoli, opposed to Libya's internationally recognized government, announced the launch of an operation to retake the city from ISIS.

"A real war has been going on in Sirte since Tuesday," the council official said. "ISIS militants and armed residents from the city have been fighting continuously," he said, adding that Sirte was also being hit by air strikes.

Libya has descended into chaos since the fall of Dictator Moammar Gadhafi in 2011. It has two parliaments and two governments vying for power, one based in Tripoli and one in Tobruk.

The defense ministry in Tripoli, which was seized last year by a militia alliance known as Fajr Libya, announced on Tuesday the launch of "an operation to liberate Sirte".

The ambassador, who answers to the internationally recognized government, said the clashes erupted after the ISIS assassinated an Imam- Muslim prayer leader- from the influential Al-Farjan tribe at the start of the week.

Since then, the terrorist have been "massacring people, even killing people in their homes," Abuhamoud charged.

ISIS, which already controls large chunks of territory in Iraq and Syria, has exploited the chaos in Libya, notably taking control in June of Sirte, 450 kilometers  east of Tripoli.