Rebels say they have advanced into the city center.
Syrian authorities have closed Aleppo airport and canceled all flights, a military source told Reuters news agency early Saturday morning.
The rebels, who launched a major offensive in northwestern Syria on Wednesday, announced on Friday that they had advanced to the center of the city of Aleppo. President Bashar al-Assad In recent days, anti-regime rebels have seized areas from Syrian government forces for the first time in years.
Source: Reuters