Syrian state forces backed by the Lebanese militant group Hizbollah hammered the central city of Homs yesterday, activists said, sparking concern from United Nations officials over thousands of civilians trapped in the city.

President Bashar al-Assad’s forces have been using heavy air raids and artillery strikes to push their offensive around the capital and the strategically located Homs, which spans central Syria’s eastern and western interna-tional borders.

Near Damascus, a well-known activist known as Mohammed Moaz died of injuries from shelling in a rebel-held sub-urb yesterday.

Moaz, whose real name was Fedaa al-Baali, was one of the first activists to let himself be filmed and recorded to try to give more credibility to his reports. He had suffered previous injuries while filming rebel operations around the capital.

He was eventually identified by security forces and they tried to blackmail him into silence by kidnapping his father. His father was let go, though he did not back down, but his brother was killed last year.

Syria’s war has killed more than 100,000 people, the pro-opposition Syrian Observatory for Human Rights says. The two-year revolt began as peaceful protests but, under a fierce security force crackdown, it degenerated into civil war. Homs city was the epicentre of the insurgency, and is the focal point of a new push by Assad’s forces.

Assad is trying to cement control of a belt of territory between his seat of power in Damascus and his stronghold on Syria’s Mediterranean coast, a move which could sever the north and south of the country where rebels have a foothold.

Video uploaded by activist groups in Homs showed fires blazing from destroyed buildings and grey smoke rolling down streets torn up by the clashes. Fighters fired rocket-propelled grenades and machineguns from battered apartment blocks.

The UN Office of the High Commissioner for Human Rights said it was “extremely concerned” about the offensive, launched by Assad’s forces on June 28.