Rebel-on-rebel violence in Syria has killed at least 1,800 this year alone
* Al Qaeda says not responsible for ISIL's actions
* ISIL has fought with other rebel groups this year (Adds background, details on rebel infighting, analyst comment)
BEIRUT, Feb 3 (Reuters) - 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 al-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.
However, the organisations that have clashed with ISIL include Jabhat al-Nusra, al Qaeda's official Syria wing, which is led by al Qaeda chief Ayman Zawahri.
In a message posted on jihadi websites on Monday, the al Qaeda General Command said ISIL "is not a branch of the al Qaeda group.
"...(Al Qaeda) does not have an organizational relationship with it and is not the group responsible for their actions,"
In April, ISIL head Abu Bakr al-Baghdadi tried to merge ISIL with Jabhat al-Nusra, defying orders from Zawahri and causing a rift.
Charles Lister, visiting fellow at Brookings Doha Center, said the al Qaeda statement "represents an attempt by al Qaeda to definitively re-assert some level of authority over the jihad in Syria" following a month of fighting and ISIL disobedience.
"This represents a strong and forthright move by (al Qaeda) and will undoubtedly serve to further consolidate Jabhat al-Nusra's role as al Qaeda's official presence in Syria."
(Reporting by Oliver Holmes in Beirut and Ali Abdelatti in Cairo; Editing by John Stonestreet)
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