Syrian warplanes have attacked the town of Qusayr as regime forces backed by Hezbollah fighters continued their assault on besieged rebels.
The Syrian Observatory for Human Rights reported a fierce overnight onslaught on Monday, both on the strategic border town near Lebanon, and Dabaa, north of the city.
Dabaa, the site of a disused military airbase that had been seized by fighters battling President Bashar al-Assad's regime, is still partly under rebel control.
The Britain-based Observatory said the latest violence had left numerous dead on both sides, but gave no breakdown.
An estimated 94,000 people have been killed in Syria since a peaceful protest movement that began in March 2011 quickly became an armed revolt when Assad cracked down on dissenters.