Dozens of Syrian troops backed by tanks have besieged the city of Zankoz, near the capital Damascus, and arrested around 20 people, a Syrian activist said Tuesday, dpa reported.
"All entrances to the city are now closed and soldiers are carrying out house-to-house searches under heavy machine gun fire in search of army defectors, whom they believe are hiding in the area," Omar Idlibi, a Lebanon-based activist told dpa.
Meanwhile, the state-run Syrian news agency SANA said Syrian authorities had killed three "armed terrorists" in the central city of Homs - which has been at the heart of anti-government protests - and confiscated weapons including grenades and sniper rifles as well as communication devices.
The government has blamed the uprising against President Bashar al-Assad, which began in mid-March, on armed gangs financed by Arab and Western countries.
More than 3,500 people have been killed in the crackdown on protesters carried out by government forces according to UN estimates.