The deaths comprise 19 children and 12 women.

At least 42 civilians were killed on Monday in a barrage of US-led air strikes on Islamic State (IS) group territory in the Syrian city of Raqqa, a monitor said.

Nineteen children and 12 women were among those killed in the raids, which hit several neighbourhoods in the northern city, the Syrian Observatory for Human Rights told AFP on Tuesday.

The death toll marked the second consecutive day of ferocious bombardment on Raqqa, more than half of which has been captured by the US-backed Syrian Democratic Forces battling the IS.