BEIRUT - An alliance of Islamist and other rebel factions battled fighters from the Islamic State in Iraq and the Levant (ISIL) across north-western Syria on Saturday in apparently coordinated strikes against the powerful al-Qaida-linked group.
Activists said dozens of fighters had been killed in the clashes, which started on Friday and may have been provoked by increasing resentment against the radical ISIL fighters, many of them foreign jihadis.
One group of fighters battling the ISIL was the newly formed Mujahideen Army, an alliance of eight brigades who accused the al-Qaida affiliate of hijacking their struggle to topple President Bashar Assad.
It said ISIL fighters were "undermining stability and security in liberated areas" through theft, kidnapping and trying to impose their own brand of Islam, and vowed to fight them until ISIL was disbanded or driven out of Syria.
The infighting amongst Assad's opponents has strengthened his hand ahead of planned peace talks in Geneva on Jan. 22. Assad, backed by Shi'ite fighters from Iraq and Lebanon's Hezbollah militia, has pushed back rebels around Damascus and in central Syria, and faces little pressure to make concessions.
Fighters from the Islamic Front, made up of several Islamist brigades which have been close with ISIL in the past, were engaged in heavy clashes with the group in northern Aleppo province, according to the Syrian Observatory for Human Rights.
The Observatory, a monitoring group based in Britain, said at least 60 people had been killed in fighting which it described as a major challenge to ISIL's control in Aleppo and neighboring Idlib province.
The ISIL and another al-Qaida affiliate, the Nusra Front, together with Islamist fighters from the Islamic Front, have eclipsed the Free Syrian Army which Western powers had hoped to build into a moderate force capable of toppling Assad.
That impotence was highlighted in November when the FSA's military command lost control of a military base and main weapons depot close to the Turkish border.