A powerful rival organisation has accused Al-Qaeda leaders of betraying the jihadist cause, in the latest widening of divisions rooted in Syria's civil war.
"Al-Qaeda today is no longer a base of jihad (holy war)," Islamic State of Iraq and the Levant spokesman Abu Mohammed al-Adnani said in a statement posted on jihadist forums.
"Its leadership has become a hammer to break the project of the Islamic State," Adnani said, adding that "the leaders of Al-Qaeda have deviated from the correct path."
"They have divided the ranks of the mujahideen (holy warriors) in every place," he said.
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Powerful rebel groups in Syria, including Al-Qaeda's designated affiliate Al-Nusra Front, have been locked in fierce fighting with ISIL since January that has killed thousands of fighters.
ISIL was initially welcomed by other rebels, who have been fighting to topple Syrian President Bashar al-Assad since 2011, but allegations of brutal abuses against civilians as well as rival opposition fighters sparked a backlash.
Some critics of ISIL have gone so far as to accuse it of serving the interests of Assad's regime by splitting rebel ranks and tarnishing the image of the uprising in the West.
Both Al-Nusra and ISIL have roots in Al-Qaeda's onetime Iraqi affiliate, the Islamic State of Iraq.
But the two have never merged, with Al-Nusra's leader rejecting a union proposed by ISIL, and Al-Qaeda chief Ayman al-Zawahiri urging ISIL to return to Iraq after its fighters moved into Syria.