Human rights activist Mustafa Osso said around 300 arrests are being made daily in the Jisr al-Shughour area, the town of Maaret al-Numan and nearby villages, where the army has been massing troops for days.
He claimed troops opened fire in the outskirts of Maaret al-Numan, a town of 100,000 on the road linking Damascus with Syria’s second-largest city, Aleppo. No casualties were reported.
The Syrian Observatory for Human Rights said dozens of tanks, armoured personnel carriers and buses used to transport anti-terrorism forces were deploying around the town of Khan Sheikhon, south of Maaret al-Numan.
Syrian President Bashar Assad has unleashed the military to crush an uprising against his rule.
More than 1,400 Syrians have been killed since mid-March.
Meanwhile, Turkish reports said a lieutenant colonel and four privates deserted the Syrian army and fled to Turkey late on Wednesday, joining a number of civil servants, other soldiers and police officers who are already sheltering in the refugee camps.
Nearly 9,000 people have sought refuge in Turkey, according to Turkish authorities.