At least 482 people have died in Syria over the past week in clashes pitting rebel factions - mostly Islamists - against the Al Qaeda-linked Islamic State of Iraq and the Levant, a non-governmental organization said Friday.

The Britain-based Syrian Observatory for Human Rights, which opposes Syrian President Bashar al-Assad, said it tallied the number of people killed in fighting between Jan. 3 and midnight Thursday in the northern provinces of Idlib, Hama, Al-Raqqah and Aleppo.

It said 85 of the dead were civilians, 21 of whom were executed by members of the Islamic State, and the rest were killed in fighting among the combatants.

At least 240 members of a loose alliance of moderate and Islamist rebel factions were killed in clashes with and car-bomb attacks carried out by the Islamic State. That figure also includes 21 insurgents who were executed by the Al Qaeda-linked group.

At least 157 members of the Islamic State were killed, 47 of whom were executed by Islamist fighters who captured them in Idlib province, according to the activist group.

The Observatory said it has received reports that the Al Qaeda loyalists may have executed dozens of civilians in Idlib.

More than 120,000 people have died in Syria since March 2011, when Assad's brutal repression of pro-democracy protests ignited an armed conflict. EFE