The Syrian army has taken a several hills southwest of the former rebel stronghold of Yabrud as they seek to secure territory between there and the Lebanese border, a security source said Tuesday.
On Sunday, backed by fighters from Lebanon's Shiite Hezbollah and local militia, they seized Yabrud after a month of shelling and air strikes.
They are now moving to secure the area along the nearby border with Lebanon, which has been a key supply route for the opposition, allowing them to transport fighters and weapons.
"The army is heading in the direction of Ras al-Ain," which is close to the border, the source in Damascus told AFP after taking the hills between there and Yabrud.
They also plan to seize the villages of Rankus, south of Yabrud, and Flita and Ras al-Maara, to its northwest.
Elsewhere, the Syrian Observatory for Human Rights said regime planes bombed the northern city of Aleppo, killing at least four people, including two children, in the Shaar district.
The violence in Aleppo came as Marcell Shehwaro, a prominent female activist detained a day earlier by rebels for refusing to wear the Islamic headscarf, was released.
The Army of Mujahedeen, which had detained Shehwaro and her friend Mohammad Khalili, issued a statement "apologising in the strongest terms" for the arrests.
Nearby, the Britain-based Observatory said troops battled Islamist opposition forces, including the Al-Qaeda affiliated Al-Nusra Front, leaving at least seven people dead on the two sides.
In the Damascus area, five people were killed by opposition mortar fire in several districts, state news agency SANA reported.
Four people were killed in the Jaramana suburb, southeast of the capital, and another in the city itself, SANA said.