BEIRUT – Clashes between government troops and rebels on Tuesday forced the international airport in Aleppo to stop all flights in and out of Syria’s largest city, while fierce battles also raged in the suburbs of the capital Damascus.

The rebels have been making inroad in the civil war recently, capturing a string of military bases and posing a stiff challenge to the regime in Syria’s two major cities – Damascus and Aleppo.

The opposition trying to overthrow authoritarian President Bashar Assad has been fighting for control of Aleppo since the summer, and they have captured large swathes of territory in Aleppo province west and north of the city up to the Turkish border.