BEIRUT: Nearly 500 people, among them 85 civilians, have been killed in a week of fighting pitting Syrian rebels against the jihadist Islamic State of Iraq and the Levant, a monitoring group said Friday.

“We have documented the killing of 482 people in the fighting — 85 civilians, 240 members of the rebel brigades and 157 members of ISIL,” said Syrian Observatory for Human Rights director Rami Abdel Rahman.

Among the civilians and rebels killed were 42 hostages who were executed in Aleppo by ISIL.

Rebels also executed 47 ISIL members, mainly in Idlib province in northwestern Syria, Abdel Rahman said.

“The rest of the deaths came during the fighting. It is likely dozens more people have lost their lives, but it is impossible to accurately document all the killings,” he added.

He called for “crimes being committed in Syria to be brought before an international court.”

Jihadist-rebel fighting has raged for a week, mainly in Aleppo, Idlib and Raqa provinces.

On Friday, rebels continued to advance in much of Aleppo and Idlib, where ISIL's presence was relatively weak, while the jihadists had the upper hand in Raqa, which has been under their control for several months.

Several rebel groups fighting President Bashar al-Assad's regime opened a new front against ISIL last week, accusing the jihadists of seeking control and committing horrific abuses in opposition-held areas.