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.

Syrian state SANA news agency on Wednesday said insurgents retreated some 20 kilometers (12 miles) from government-held Hama, Syria’s fourth-largest city, as government troops backed by

Syrian rebels launched a surprise attack on Saturday and quickly advanced through several provinces in the north and northwest of Syria, including the city of Aleppo, the country’s second largest city.