Syrian rebels have reportedly given a powerful Al-Qaeda-linked group 24 hours to surrender.
The ultimatum comes after two days of deadly rebel infighting in the northern provinces of Idlib and Aleppo.
Syrian opposition fighters from the Army of Mujahedin, a newly formed alliance of Islamic groups, have declared war against the Al-Qaeda-linked Islamic State of Iraq and the Levant (ISIS).
Ahmad al-Khatib, an opposition activist in Idlib, told AFP that the rebels had given the ISIS an ultimatum to surrender by the afternoon of January 4.
ISIS fighters flocked to Syria soon after the civil war broke out. But their brutal tactics, including public executions and the kidnapping, torture, and assassination of rival rebels, have turned many locals and rebels against them.
Syria's main opposition grouping, the National Coalition, on January 4 endorsed their fellow rebels' fight against ISIS.
Based on reporting by AP and AFP