Clashes have been reported near the airport of the Syrian capital, Damascus, as internet and mobile phones continued to be cut off for a third day, Belfast Telegraph reported.

A day earlier, 20 Lebanese were killed inside Syria while fighting alongside rebels to topple President Bashar Assad. The news heightened tensions in neighbouring Lebanon.

Lebanese troops deployed to the northern city of Tripoli after the deaths were announced and Sunni Muslim gunmen fired into the air in tribute.

The vast majority of Syria's rebels are also Sunnis. Assad - along with his most elite troops - belongs to the Alawite sect, an offshoot of Shiite Islam.

The Britain-based Syrian Observatory for Human Rights and Syria-based activist Mohammed Saeed reported the heavy fighting and shelling near Damascus' airport.

The civil war has forced hundreds of thousands of Syrians to flee the country, and many more are internally displaced. Fighting has also spilled into Turkey and other neighbouring countries.