The advance on Aleppo followed a shock offensive launched on Wednesday, as fighters swept through villages and towns.

Thousands of Syrian insurgents fanned out inside Aleppo in vehicles with improvised armor and pickups, deploying to landmarks such as the old citadel on Saturday, a day after they entered Syria's largest city facing little resistance from government troops, according to residents and fighters.

With Russia and Iran devoting much of their resources to their own wars, the Syrian rebels took Aleppo with little resistance from the Assad regime.