Syria's army battled rebels for control of the ancient Christian town of Maalula near Damascus on Saturday, a security official told AFP, a week after opposition fighters took the area.
At the same time, rebel units were fighting jihadists in the east, near the border with Iraq, as were Kurdish fighters in Hasakeh province in the northeast, the Syria Observatory for Human Rights said.
"The army is continuing its mission in Maalula. There are still some terrorist pockets in the north of the town, in the Al-Safir hotel and its surroundings, as well as in the hills surrounding the town," the official from the security services said on condition of anonymity.
President Bashar al-Assad's regime has consistently labelled opponents as "terrorists" since the outbreak of the revolt in March 2011 that has killed more than 110,000 people.
"The army has made some progress," the official added, saying the battle for Maalula has been hard because the army did not want to bomb the town.
The Britain-based Observatory said the air force was carrying out strikes to support the ground operation, with the security source saying the town itself was not being targeted to protect its ancient churches and other heritage sites.
Picturesque Maalula is nestled under a large cliff, whose summit is controlled by the rebels, making it difficult for the army to advance.
Signup to our newsletter and follow us on Facebook and Twitter!
Last week, the Observatory and residents said rebel forces, including jihadists linked to Al-Qaeda, had overrun the town.
Civilians started fleeing the town for Damascus and the neighbouring Sunni village of Ain al-Tine, fearing an imminent escalation.
On Tuesday, rebels announced they would withdraw from Maalula, but that this was "conditional" on pro-regime forces not taking their place.
The town, home to about 5,000 people, is strategically important for rebels, who are trying to tighten their grip on Damascus and already have bases circling the capital.
In other developments, the Observatory said regime air strikes elsewhere had killed three women and a child near Damascus.
In Deir Ezzor province, near the Iraqi border, it said there was fighting between rebels and units of the jihadist Islamic State of Iraq and the Levant (ISIS) in Albu Kamal, with five people killed.
And in Hasakeh province, in the northeast, Kurdish fighters clashed with elements of ISIS and another jihadist group, the Al-Nusra Front.
In July, the Kurds drove the jihadists out of the area after fierce fighting.