Syria state media say government troops are battling insurgents inside the country's largest city Aleppo for the first time since 2016.

The push into Aleppo followed weeks of simmering low-level violence, including government attacks on opposition-held areas. Turkey, which has backed Syrian opposition groups, failed in its diplomatic efforts to prevent the Syrian government attacks ...

The Syrian military said on Saturday that rebels had entered large parts of Aleppo city during an offensive in which dozens of soldiers had been killed, forcing the army to redeploy - the biggest challenge to President Bashar al-Assad in years.