BEIJING, Feb. 24 (Aljazeera) — More than 400 people have been killed in Eastern Ghouta, a monitoring group said, as Syrian government forces backed by Russian warplanes continued their aerial bombardment of the rebel-held area.

The Syrian Observatory for Human Rights said on Thursday that at least 403 people were killed in the "hysterical attack" that began on Sunday, including 150 children. Almost 2,120 others were wounded.

UN special envoy for Syria, Staffan de Mistura, stressed the urgent need for a ceasefire in comments made before Thursday's UN Security Council meeting.

"The humanitarian situation in Eastern Ghouta is appalling and, therefore, we need a ceasefire that stops both the horrific heavy bombardment of Eastern Ghouta and the indiscriminate mortar shelling on Damascus," he said.