A Syrian rebel commander who fought alongside al-Qaeda founder Osama bin Laden and was close to the group’s current chief, Ayman al-Zawahiri, was killed in a suicide attack Sunday, intensifying infighting among rival Islamist fighters.

In a separate bombing, at least 14 people were killed and 70 wounded when a car bomb went off Sunday near a field hospital in a Syrian town on the border with Turkey that serves as a main supply line for rebels fighting President Bashar al-Assad, activists said.

The Syrian Observatory for Human Rights said Abu Khaled al-Soury and six comrades in the Salafist group Ahrar al-Sham were killed by the Islamic State of Iraq and Syria (ISIS), an al-Qaeda splinter group. The Britain-based organization said Soury — also known as Abu Omair al-Shamy — had fought in Iraq and Afghanistan.

Soury’s death will fuel the infighting among Islamists battling the Assad regime. The rivalry has killed hundreds of fighters in recent months, rebels said. Sources said that by killing Soury, ISIS had taken the war between militant Islamist factions to a new level and that the decision to kill him must have been made by the ISIS high command, most probably its leader Abu Bakr al-Baghdadi, who last year fell out with ­Zawahiri and the leader of the Syrian al-Qaeda affiliate Jabhat al-Nusra.

“Sheik Abu Khaled was influential among the jihadists, especially among the ISIS fighters. He was the only one who could make them change their minds and stop the fighting,” another source said.

The bombing near the hospital happened in the town of Atmeh, which has been held by a loose coalition of Islamist rebels who drove the ISIS fighters from the town two months ago.

The target was a hospital owned by Ghassan Aboud, a ­pro-opposition businessman who owns Orient Television, which has been a vehement critic of ISIS.

— Reuters