A Syrian government air strike aiming to stop a Turkish convoy reaching a rebel-held town in northern Syria has killed three civilians, Turkey alleges.

Another 12 people were injured in the attack in Idlib province on Monday, the Turkish defence ministry said.

Idlib, one of the few areas not under government control, was supposed to be protected by a buffer zone agreed with rebel-backing Turkey last year.

But government assaults have been on the increase since April.

Hundreds of civilians have already been killed as a result, and there are fears many more will die if the situation continues to escalate.