BEIRUT: The Syrian army and rebel groups engaged in fierce battles early on Sunday on a critical front in eastern Ghouta where government advances have in effect splintered the insurgent enclave into three, a war monitor said.

More than 1,100 civilians have been killed in the onslaught on the biggest rebel stronghold near Damascus since it began three weeks ago with a withering bombardment, said the Syrian Observatory for Human Rights.

It said there was intense fighting on several fronts accompanied by a government artillery barrage, continuous air raids and attacks by helicopters.