Al-Qaeda's general command said on Monday it has no links with the Islamic State in Iraq and the Levant (ISIL), in an apparent attempt to assert authority over the Islamist militant groups involved in Syria's civil war.
Small but powerful, ISIL has been caught up in battles with other Islamist insurgents often triggered by disputes over authority and territory, and has also clashed with secular rebels.
The internecine fighting - among the bloodiest in the three-year conflict - has undermined the uprising against President Bashar Assad and dismayed Western powers pushing for peace talks.
Rebel-on-rebel violence in Syria has killed at least 1,800 this year alone.
ISIL follows al Qaeda's hard-line ideology and, until now, the two groups were widely believed to be linked.