Thousands of residents have fled eastern Ghouta in Syria- according to the rescue group the white helmets.
The rebel-held district has been bombarded by forces loyal to the Syrian president and aid has been blocked from getting in.
The UN said: "This collective punishment of civilians is simply unacceptable."
The White Helmets say over 650 people, including around 150 children,are now believed to have been killed in the area just to the east of the capital Damascus, in the past two weeks alone.
Satellite images show two images of Eastern Ghouta taken one week apart following days of military strikes.
The UN Security Council ordered a ceasefire that had impact on the number of casualties with both residents and aid groups reporting continued air raids.
The Syrian Observatory says President Assad's forces now control one quarter of the area.