Syrian forces in Yabroud were in the final stages on Sunday of clearing out rebels holed up there for months and had begun dismantling roadside bombs laid by the militants, a military source told Reuters.
Capturing Yabroud, the last major rebel bastion near the Lebanese border north of Damascus, would help President Bashar al-Assad secure the land route linking his Mediterranean coastal stronghold with the capital Damascus, and choke off a cross-border rebel supply line from Lebanon.
The source said most of the insurgents had pulled out of Yabroud around dawn, a day after pro-government forces had entered eastern districts of the town and captured several strategic hilltops.
A fighter in Yabroud from the Nusra Front, al Qaeda's official affiliate in Syria, confirmed to Reuters the rebels had decided to pull out and said they were heading towards nearby villages including Hosh Arab, Rankos and Fleita.
He said they did not plan to withdraw across the Lebanese border to Arsal, a crossing point 20 km (13 miles) to the northwest which rebels and refugees have used regularly.
The government has been making incremental gains along the land route as well as around Damascus and Aleppo in the past months, regaining the initiative in a conflict entering its fourth year.
More than 140,000 people have been killed in the increasingly sectarian civil war, which began with mass street protests against Assad but turned into an armed insurgency after a violent security crackdown on demonstrators.