Syrian government air strikes on rebel-held neighbourhoods of divided second city Aleppo killed at least 15 civilians on Wednesday, a monitor said.

The Syrian Observatory for Human Rights said at least 10 of the dead came in raids just outside the Al-Bayan hospital in the Shaar neighbourhood.

Two children were among four people killed in strikes on the Al-Marja district using barrel bombs -- crude explosive devices packed with shrapnel and usually dropped from helicopters, the Observatory said.

One person was killed in a strike on the Al-Maadi neighbourhood.

Rescue workers -- known as the White Helmets -- gave a higher toll of 23 dead.

Al-Bayan hospital said a member of its staff had been wounded in the strikes and that the building had been evacuated.

An AFP photographer said the hospital entrance had been damaged but the rest of the building was intact.

Aleppo was once Syria's commercial powerhouse, but it has been a battleground since 2012 when rebels seized the east of the city confining the army to the west.

Since then, the rebels have repeatedly pounded government-held areas with rocket and mortar fire, while the army has hit rebel neighbourhoods with air strikes

A truce brokered by Russia and the United States in February has been persistently violated in and around Aleppo.

Source: AFP