The leader of Syria’s most powerful insurgent group has toured the seized city of Aleppo in a surprise visit, for the first time since the group captured large parts of the city last weekend, as fierce fighting intensifies in the government-led counter-offensive in northern Hama.

The Syrian military has rushed in reinforcements to push back insurgents from advancing farther into the northern Hama countryside after they seized Aleppo in a surprise offensive

Syrian rebel fighters are advancing southward after capturing much of Aleppo, Syria’s largest city, posing the most serious challenge to President Bashar al-Assad in years amid the country’s civil war,