Heavy fighting raged on Monday (May 27) around the strategic Syrian border town of Qusair, opposition activists said.
The city faced ground and air bombardment from government forces as rebels fought back against Hezbollah fighters.
Video clips, said to be filmed on Sunday (May 26) and Monday and uploaded to a social media website, appear to show a blast from an air strike, a mortar bomb landing and heavy machinegun fire being unleashed on Hezbollah fighters.
The Lebanese Hezbollah fighters - in support of troops loyal to President Bashar al-Assad -- were advancing in areas around Qusair, pressing a sustained assault on a town long used by rebels as a way station for arms and other supplies from Lebanon, opposition activists said.
Rebel reinforcements from elsewhere in Syria were trying to relieve the pressure, but their attacks had bogged down on the outskirts.
For Assad, Qusair is a crucial link between Damascus and loyalist strongholds on the Mediterranean coast. Recapturing the town, in central Homs province, could also sever connections between rebel-held areas in the north and south of Syria.
Presented by Adam Justice