"Government forces have managed to lift the siege on the Wadi al-Deif and al-Hamdiya garrisons after the army went around the rebel fighters and attacked them from behind," the Syrian Observatory for Human Rights reported.

Troops "now control two hilltops on either side of the Damascus-Aleppo international highway" reopening a supply route for the army, Observatory director Rami Abdel Rahman told AFP.

The watchdog said two military trucks carrying materiel and soldiers have since been spotted passing through the area for the first time in months. The area is in the countryside near the strategic town of Maaret al-Numan, which fell to rebel forces last October.

Rebels began blocking military supply routes north and to the nearby Wadi al-Deif and al-Hamdiya army bases after they seized Maaret al-Numan, which lies on the Damascus-Aleppo highway.

There are also reports of clashes between government forces and militants in several other cities, including Aleppo, Homs, Latakia, Deir al-Zour and Damascus suburbs.

Syria has been gripped by a deadly unrest since March 2011, and many people, including large numbers of government forces, have been killed in the violence.

Several international human rights organizations have accused foreign-backed terrorists operating in Syria of committing war crimes.