A senior figure in an Al-Qaeda-linked group in Syria has been killed in a bloody dispute with rebel factions that has raged for more than three weeks across opposition-held parts of the country, activists and an Iraqi intelligence official said Monday.

Heavy fighting between the Islamic State of Iraq and Greater Syria (ISIS) and rival rebels has left more than 1,400 people dead across the country since Jan. 3, erupting after months of growing resentment against ISIS’ heavy-handed tactics in the territory under its control.

The senior militant, an Iraqi who went by the nom de guerre of Haji Bakr, was killed earlier this month in the town of Tal Rifaat in the northern province of Aleppo, according to the Britain-based Syrian Observatory for Human Rights monitoring group. That corresponded to reports provided by two activists based in the city of Aleppo, Hasan Kattan and another who spoke on condition of anonymity for security reasons.