Syrian security forces are reportedly widening an operation in the north of the country aimed at cracking down on anti-government protests.
Troops pushed towards the northern town of Maarat al-Numaan after detaining hundreds of people in a sweep through villages near the town of Jisr al-Shughur, the Reuters news agency reported, citing residents who fled the area.
Refugees have poured across the Syrian border into neighbouring Turkey to escape the government's operation, the site of an intense military takeover on Sunday.
More than 8,000 Syrians have so far crossed the border with Turkey to escape the violence, and an estimated 10,000 more are waiting for the opportunity to cross.
Witnesses said those still in Syria had taken shelter among trees near the border since forces moved into the northwestern province of Idlib.