Air strikes thought to have been carried out by Russian jets on a rebel-held residential area in northwestern Syria have killed 44 civilians, a Britain-based monitor said on Friday.

Six children were among those killed when the strikes hit the Zardana area of Idlib province late on Thursday, the Syrian Observatory for Human Rights said. The Russian defence ministry dismissed the Observatory's reports of strikes on Zardana as having "nothing to do with reality", in a statement carried by the TASS news agency.