Syrian government and opposition factions say Syrian armed groups have launched a large-scale attack on areas controlled by government forces, setting off fierce clashes for the second day.

Russian and Syrian warplanes bombed rebel-held north-west Syria near the border with ­Turkey on Thursday to push back an ­insurgent offensive that captured territory for the first time in years, Syrian army and rebel sources said.

Russian forces in Syria are under attack from rebel groups in the Syrian capital, Aleppo, in response to increased strikes.