Al-Qaeda's representative in Syria was killed Sunday in a suicide bombing, the rebel Islamic Front announced on its Twitter account.
Abu Khalid al-Suri, who was appointed last year by Al-Qaeda chief Ayman al-Zawahiri as his representative, died in the northern city of Aleppo, said the group.
The Islamic Front is the biggest rebel alliance in Syria, and it has been locked in battle with the jihadist Islamic State of Iraq and the Levant (ISIL).
Suri was a commander of Ahrar al-Sham movement, one of the main rebel groups in the Islamic Front alliance.
His death in a suicide bombing in Al-Halq area of Aleppo was also confirmed by the Syrian Observatory for Human Rights and on jihadist websites.
Observatory chief Rami Abdel Rahman said he died along with six comrades when a jihadist from the rival ISIL group blew himself up at an Ahrar al-Sham post in Al-Halq.
Suri fought in Afghanistan and Iraq and "was known to be close to Osama bin Laden," the Al-Qaeda founder who was killed by US troops in Pakistan in 2011.
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Jihadist websites also described Suri as a "travelling companion of Sheikh al-Zawahiri" and "among the companions of Sheikh Osama bin Laden".
Last year, Zawahiri ruled that ISIL and Al-Qaeda's affiliate in Syria, Al-Nusra Front, should operate as separate entities after the head of ISIL announced a merger of the two groups.
At the time Zawahiri appointed Suri as his representative in Syria to arbitrate on any issues resulting from the cancellation of the merger of the two factions.
ISIL, which grew from Al-Qaeda's onetime Iraqi affiliate, is facing a widespread backlash from an array of rebel brigades angered by its abuses against civilians and rival opposition fighters.
The group has ignored Zawahiri's orders to return to Iraq.
Earlier this month, Al-Qaeda cemented its split with ISIL as infighting between the rebels increased.
"Al-Qaeda announces it is not linked to the Islamic State of Iraq and the Levant, as it was not informed of its creation... (and) did not accept it," a statement said.
ISIL "is not a branch of Al-Qaeda, has no links to it, and the (Al-Qaeda) group is not responsible for its acts."