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

Syrian rebels in the last opposition enclave in northern Syria launched on Wednesday a wide-scale military operation against the Syrian army and seized territory in the first such advance in years, army and rebel sources said.