Forces opposed to President Bashar al-Assad have captured the Aleppo airport and are attacking the western city of Hama, according to local officials and a Britain-based war monitor.

At least 372 people have been killed since rebels launched a surprise offensive on Wednesday, according to observers.

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,