Three weeks of fighting between rival Syrian rebel groups has left 500 people dead in the biggest remaining opposition stronghold in the Damascus region, a monitoring group said on Tuesday.
About 50 people were killed on Tuesday alone in clashes in the eastern Ghouta area outside the capital, Rami Abdel-Rahman, director of the Syrian Observatory for Human Rights, told dpa.
The fighting pits the hardline Army of Islam, one of Syria's largest rebel forces whose main stronghold is the Ghouta town of Douma, against rival groups including the Syrian branch of al-Qaeda.
The Army of Islam, which is participating in the opposition delegation to stalled peace talks in Geneva, has accused its rivals of allowing government forces to gain ground in the area thanks to the infighting.
The eastern Ghouta is strategically vital as the largest remaining opposition-held area in the Damascus area. Government forces have retaken several areas near the capital and forced rebels in others to sign up to local truces, often by using starvation as a form of coercion.
According to a local resident, civilians trapped in their homes amid the fighting have been among those killed in the clashes.
Abdel-Rahman stated that most of the dead were combatants, but did confirmed that at least 12 civilians have been killed during the conflict.
The eastern Ghouta was also the scene of chemical weapons attacks (widely blamed on the Syrian government) that killed hundreds of civilians in 2013.