Russia is undermining efforts to find a political solution to ending the conflict in Syria because of its constant air strikes, Nato's secretary-general has said.

Peace talks were suspended this week as Syrian government forces, backed by the Russian military, launched a fresh offensive against rebels in Aleppo which has reportedly led to thousands of people fleeing towards its borders.

Jens Stoltenberg said on Friday (5 February) the air strikes posed a particular problem for Nato member Turkey, which is already in dispute with Moscow after Ankara shot down a Russian jet it accused of violating its airspace. He said: "The intense Russian air strikes mainly targeting opposition groups in Syria are undermining the efforts to find a political solution to the conflict," adding that increased Russian activity "creates risks and heightens tensions and is of course a challenge for Nato".

Earlier, Turkey had dismissed Russian claims that it was planning to invade Syria with President Recep Tayyip Erdogan calling the accusations "laughable". But the comments by Nato's chief will be a further blow to relations between the alliance and Moscow which are at their lowest since the Cold War after Russia's annexation of Crimea from Ukraine in 2014 and accusations the Kremlin is supporting pro-Russia separatists in eastern Ukraine.

Meanwhile, Russia said it could not commit to stronger control over its conventional weapons in Europe while Nato increases its activities. Russian Deputy Defense Minister Anatoly Antonov said if the 2011 Vienna treaty on conventional arms control in Europe is updated, it needed to be more stringent. Under the terms of the treaty, Russia and NATO exchange inspectors to share information on military activities in Europe.

But Antonov said: "The list of strategic systems is broadening as modern conventional weapons are comparable with nuclear weapons and therefore just counting cannons and tanks is not enough," according to Radio Free Europe.