Around 500 people have been killed in a week-long fighting between Syrian rebels and rivals from a jihadist group linked to al-Qaeda, a pro-opposition watchdog group said Friday.
Fighting between opposition forces led by the Free Syrian Army and mainly foreign fighters from the Islamic State in Syria and the Levant (ISIL) have been raging for days in northern and eastern Syria, dpa reported.
The Britain-based observatory reported that ISIL fighters had overnight seized a headquarters of al-Nusra Front, a jihadist group, in the province of al-Raqqa in eastern Syria.
Attacks by ISIL on rival rebel groups in recent months, as well as kidnappings of opposition activists, has led to widespread anger against the group, whose formation was announced in April by Iraqi al-Qaeda leader Abu Bakr al-Baghdadi.
The Syrian conflict, which erupted nearly three years ago, has seen several radical groups impose strict Islamic rule in areas under their control, triggering fears that the country is turning into a hotbed of Islamist militancy.