Russian President Vladimir Putin has bitterly condemned the downing of a Russian jet on the Turkey-Syria border.

He described it as a "stab in the back" committed by "accomplices of terrorists".

Turkey says its jets shot at the plane after warning that it was violating Turkish airspace. But Moscow says it never strayed from Syrian airspace.

US President Barack Obama has said Turkey has a right to defend its territory and airspace, and that the incident pointed to ongoing problems with Russia's military operations in Syria.