(CNN) - More than 200 civilians have been killed since Monday in Syrian government airstrikes on parts of rebel-held Eastern Ghouta near Damascus, the Syrian Observatory for Human Rights said Thursday. Among the deaths were 54 children and 41 women.
The four days of airstrikes by Russian-backed Syrian forces on the besieged area east of the Syrian capital also have left at least 700 civilians injured, according to the UK-based group.
The Eastern Ghouta area has been surrounded by Syrian forces for more than four years, with the siege intensifying in May when government forces conducted a large-scale offensive.
Airstrikes escalated in recent days after a Russian warplane was shot down over the weekend in the rebel-held northwestern province of Idlib.
Relying on information from activists on the ground, the Syrian Observatory for Human Rights said it counted 213 civilian deaths over four days: 31 on Monday, 81 on Tuesday, 41 on Wednesday and 60 on Thursday.
Syrian activists report rapidly deteriorating conditions -- the worst in four years -- in the area controlled by various Islamic rebel groups, with hundreds of thousands of residents struggling from shortages of food and medical supplies.
The Eastern Ghouta area was supposed to be a "de-escalation zone," according to a peace agreement struck by Russia, Turkey and Iran in May.
About 400,000 Syrians have been killed since the conflict erupted in 2011, according to the United Nations.