At least 14 children were among 20 people killed in an air strike in Syria's northwestern Idlib province at dawn on Wednesday, the Syrian Observatory for Human Rights monitor said.

The monitor said the strikes were believed to have been carried out by Russian warplanes on the provincial capital Idlib city, which is controlled by jihadists and their Islamist allies.

The Observatory, which relies on a network of sources inside Syria for its information, says it determines whose planes carry out raids according to type, location, flight patterns and munitions used.