Activists said at least 32 people have been killed during fresh violence in Syria.
The latest bloodshed centred in Rastan, where opposition sources said rebels killed 23 members of President Bashar al-Assad's security forces in fighting.
Heavy government shelling of the town killed nine people.
Reports from Syria cannot be independently verified as state authorities have barred international journalists and rights groups.
Shelling began yesterday and intensified overnight, activists said. The violence is a new blow to a ceasefire declared by peace envoy Kofi Annan a month ago.
"Shells and rockets have been hitting the town since 3am at a rate of one a minute. Rastan has been destroyed," a member of the rebel Free Syrian Army (FSA) in Rastan who declined to be named told Reuters by satellite phone.
He said among those killed was Ahmad Ayoub, an FSA commander whose fighters were battling the army forces which he said were made up of elite units and members of Military Intelligence.
The British-based Syrian Observatory for Human Rights said fighting began at dawn on Monday and that rebels destroyed three armoured personnel carriers and seized two others, capturing around 15 soldiers.
Syria's uprising began as a peaceful protest movement but has become increasingly militarised as rebels fight back against Assad's violent crackdown. Syria restricts media access, making it difficult to verify accounts of the unrest.
Syria's Sunni majority is at the forefront of the uprising against Mr Assad, whose minority Alawite sect is an offshoot of Shia Islam. Assad's government says it is fighting a terrorist attempt to divide Syria.
Rastan has in the past been a major source of Sunni Muslim conscripts who provide most of manpower in the military, which is dominated by Alawite officers.
Sunni officers from Rastan began defecting after security forces shot dead dozens of demonstrators in the town and arrested many of its notables.
The area was scene of the first serious armed confrontations between army defectors and loyalist forces last year. Assad's forces regained control of the city several times but it has kept falling back into rebel hands.
