Syrian rebels pressed an offensive in the Damascus and Aleppo provinces , in an escalation that has killed 194 fighters on both sides in the past three days, a monitoring group said Monday.
The Syrian Observatory for Human Rights, a pro-opposition group with a network of activists across Syria, said rebels had advanced in Eastern Ghouta in recent fighting,  seizing some small villages and the once government-held town of Deir Attiya.
The Britain-based Observatory said it had documented about 100 deaths on the rebel side on Friday and Saturday in Eastern Ghouta, and more than 60 among forces fighting for Assad.
But it said there were likely to be more deaths that had not been documented.
“This battle has been one of incredible human losses,” said Rami Abdelrahman, head of the Observatory. “The fighting is spreading all over the eastern suburbs.”
“In the past three days, the rebels have taken over small villages and checkpoints east of Damascus and southeast of Aleppo, after launching counter-offensives on those fronts,” he added.
It began on Friday when rebel units attacked a string of military checkpoints encircling the opposition-held suburbs in an area known as Eastern Ghouta, which has been under siege for more than six months.
Local and international aid workers say Assad's forces appeared to be trying to starve out residents - indiscriminately affecting civilians as much as rebel fighters.
The blocka has cut off rebels' weapons supplies and helped turn the tide of fighting around the capital in Assad's favour.
“It is a ferocious fight between the two sides because it's a struggle over our ultimate fate here,” said Bara Abdelrahman, a media activist with the rebel Islam Army brigades in the area.
The conflict in Syria has killed more than 100 000 people, according to the United Nations, and is also destabilising Syria's neighbours.