Thousands of Syrian troops backed by armour opened fire in the resort town of Zabadani on the border with Lebanon on Sunday, a day after heavy fighting in the area between army defectors and loyalist forces, residents and activists said.

Armoured vehicles fired machineguns and anti-aircraft guns as they entered the town, in the foothills of the Anti Lebanon Mountains, 35 kilometres (22 miles) west of Damascus.

Troops combed flat farmland near the town on Saturday looking for defectors, ransacked homes, seized cars and arrested at least 100 people, including three female college students suspected of participating in pro-democracy protests, they said.