Smoke blankets the Syrian border town of Qusair, as heavy fighting rages in the strategic city.<br/> <br />Syrian government forces and Hezbollah fighters were reported to be pressing a sustained assault on the town, while rebels fought off ground and air bombardment.<br/> <br />Video footage of the fighting, said to be shot there on Sunday and Monday, cannot be independently verified by Reuters.<br/> <br />For President Bashar al-Assad, Qusair is a crucial link between Damascus and loyalist strongholds on the Mediterranean coast.<br/> <br />Recapturing the town could also sever connections between rebel-held areas in the north and south of Syria.<br/> <br />Thousands of civilians have been trapped by the violence said United Nations human rights chief Navi Pillay on Monday.<br/> <br />(SOUNDBITE) (English) UNITED NATIONS HIGH COMMISSIONER FOR HUMAN RIGHTS, NAVI PILLAY, SAYING:<br/> <br />"I am extremely concerned at current reports, suggesting that hundreds of civilians have been killed or injured, and thousands may re
