An advance team of six UN observers has arrived in the Syrian capital to monitor the country’s ceasefire, which appeared to be rapidly unravelling today as regime forces pounded the opposition stronghold of Homs with artillery shells and mortars, activists said.

Syrian troops have resumed their shelling of residential neighbourhoods dominated by rebels in the central city of Homs, activists say.

Shells slammed into the central Syrian city of Homs today, killing more than two dozen people, activists said, as Syria’s government defied ceasefire demands and international efforts to boost the rebels.