The Syrian Revolution General Commission (SRGC), a network of activists on the ground, said an operation had begun "to liberate the Taftanaz airbase".

The Syrian Observatory for Human Rights, a Britain-based watchdog, said "heavy fighting" had broken out near the airport, in Idlib province where rebels have made significant gains in recent days.

The rebels were also reported to have taken three military positions in Douma, a northeastern suburb of Damascus, and an air force position in Idlib.