Turkish forces are said to have shot down a Russian jet after it reportedly flew into the country’s airspace.
It has been reported by eyewitnesses that there was a large explosion in the town of Huraytan, northern Syria.
The Russians – who have announced plans to increase the number of strikes against ISIS targets – have also clashed with Turkey, after one of their bombers violated Turkish airspace.
But neither side has yet said whether rumours of another of Russia’s planes was shot down in a separate confrontation.
According to the Daily Express, one journalist tweeted that three Turkish planes had been responding to ‘mysterious’ lock-ons from MIG-29 jets, which are used by Putin’s forces.
A spokesman for Nato said it had so far received no reports of a plane being shot down.
Nato and the US have been alarmed at violations of Turkish air space by Russian planes.
Earlier this week Nato urged Moscow to end air strikes on the Syrian opposition as fighter jets were scrambled to intercept Russian warplanes that had violated Turkish airspace.
Turkey sent two F-16 jets to head-off a Russian fighter that violated its airspace near the Syrian border last weekend.
At an emergency meeting, NATO warned of the ‘extreme danger’ of such violations and condemned the incursions.
‘The Turkish Armed Forces are clearly instructed. Even if it is a flying bird, it will be intercepted,’ he added, while playing down the idea of ‘a Turkey-Russia crisis’.