Syrian forces on Thursday began a fresh offensive in the province of Homs, dpa quoted opposition activists as saying. The shelling was targeting Al-Rastan city, a stronghold of the militant Free Syrian Army (FSA), said Rami Abdel Rahman, the spokesman for the Syrian Observatory for Human Rights. "The regime wants to destroy the city as it is totally under the control of the FSA," he said. The province was the target of a month-long siege and bombardment by troops loyal to President Bashar al-Assad in February, according to the opposition. The continuing violence in Syria is undermining the mission of 200 United Nations observers who are monitoring a ceasefire that went into effect on April 12. The UN's truce is part of a plan proposed by UN-Arab League envoy Kofi Annan to end 14 months of bloodshed in Syria.