Syrian regime forces Friday sought to mop up the final pockets of rebel resistance north of Qusayr, after retaking the key town that was an insurgent bastion for a year, a watchdog said.
The Syrian Observatory for Human Rights said President Bashar al-Assad's forces were also sending reinforcements to the northern province of Aleppo, where large swathes of territory have been in rebel hands for months.
"Clashes broke out at dawn between the army and rebels on the outskirts of Dabaa village" north of Qusayr near the border with Lebanon, said the Britain-based group which relies on activists and medics on the ground for its information.
Official Syrian media had reported that Dabaa fell on Thursday.
Al-Manar, the television channel of Lebanon's Shiite Hezbollah movement which was instrumental in helping Assad's forces to seize Qusayr, quoted a general as saying his troops had launched a surprise attack.
This was aimed at "the liberation of Dabaa" from rebels, he said.
A second rebel bastion north of Qusayr, Eastern Bweida where rebels and many wounded civilians fled after the fall of Qusayr, was still being bombarded by the regime.
"Four rebels were killed on Thursday evening while trying to evacuate wounded," Observatory director Rami Abdel Rahman told AFP.
"The army is seeking to impose its complete control of Qusayr and the surrounding area," he said.
"It is leaving no way out for the rebels, and also not for the wounded or for civilians. It wants to annihilate the rebels or take them prisoner."
At least 15 rebels were killed on Thursday in bombardments of Dabaa and Eastern Bweida, the Observatory said.
Analysts say regime forces will now turn their attention on the central city of Homs, where some areas are still rebel in rebel hands.
The Observatory said government forces were also massing "in their thousands" in Aleppo province in the north, aiming primarily to take insurgent-held territory along the border with Turkey.
"They want to cut rebel supply lines from Turkey," it said, adding that Hezbollah had sent "dozens of its men to train Syrian Shiites to fight".
Assad's regime is Alawite, an offshoot of Shiite Islam, while the rebels seeking to topple it are mainly Sunni Muslims.
Since the revolt began in March 2011, more than 94,000 people have been killed according to Observatory estimates, and nearly six million people have been displaced, either internally or as refugees abroad.