Syrian opposition forces have taken control of the majority of the country’s second largest city Aleppo, according to video verified by CNN and residents in the city.

Russian and Syrian warplanes targeted insurgents in an Aleppo city suburb on Saturday, two Syrian military sources said, after the rebel fighters penetrated the heart of the city in Syria's northwest in a surprise attack the previous day.

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