At least 51 civilians, including four children, were killed in air raids and shelling attacks on Saturday in Syria's battleground city Aleppo and the neighbouring countryside, a monitoring group said.

Syrian air force raids left 15 people dead in rebel-held areas in the east of Aleppo city. Nine civilians died in rebel shelling on the government-held west, the Syrian Observatory for Human Rights said.

Another 27 people were killed in Syrian and Russian raids targeting a string of towns in the west of Aleppo province, the Britain-based group added.