The Syrian military pounded the rebel-held central town of Qusayr, killing 13 people, in an apparent preparation for a ground assault, a watchdog said.
The Syrian Revolution General Commission, a network of activists on the ground, also reported an intense bombardment of Qusayr, which the Syrian regime has been trying to recapture.
The Qusayr district of Homs province has been the focus of fierce fighting between government forces and the rebels in recent weeks.
Regular troops have been bolstered by militiamen and by fighters of Lebanese militant group Hezbollah, a staunch Damascus ally.
The area is considered strategically important because it connects the capital to the Mediterranean coast.