Members of the Free Syrian Army's "Freedom for the River Assi Brigade" run as they take part in an attack on Syrian regime forces in Homs province
Troops stormed a village in central Syria on Sunday and rained shells on rebel strongholds Douma and Rastan, monitors said, as a UN-backed truce entered a second month looking in tatters.
The assault on Al-Tamanaa Al-Ghab village in Hama province, a hotbed of opposition to President Bashar al-Assad's regime, killed five civilians, wounded 18 and saw houses torched, the Syrian Observatory for Human Rights said.
Clashes between troops and deserters in the southern province of Daraa, meanwhile, saw five soldiers killed, it said. Two civilians died in the crossfire, reports AFP.
The watchdog said at least 25 people -- 18 civilians, five soldiers and two rebels -- were killed in a surge of violence in various flashpoints on Sunday, despite a ceasefire brokered by UN-Arab League peace envoy Kofi Annan that was supposed to take effect on April 12.
The Local Coordination Committees (LCC), a coalition of opposition activists on the ground, said the Syrian army shelled Douma near Damascus on Sunday and that heavy gunfire was also heard in the suburb of the capital.
The LCC also said the town of Rastan in central Homs province also came under heavy bombardment, with one activist reporting "one rocket a minute" slamming into the rebel-hand town.
The violence in Syria has escalated over the past week, despite the arrival of more ceasefire observers. The UN mission in Syria said on Sunday it now has 189 military observers on the ground, nearly two-thirds of its planned strength of 300.
The observers are tasked with shoring up the ceasefire, which has been broken daily by both sides to the conflict.
Twin suicide bombings in Damascus on Thursday that killed 55 people and wounded 372 have raised fears that extremist elements are taking advantage of the deadlock in Syria to stoke the unrest.
Al-Nusra Front, an Islamist group unknown before the Syrian revolt, released a video on Saturday claiming responsibility for the Damascus attacks as revenge for regime bombing of residential areas in several towns and to avenge Sunnis killed by forces loyal to Assad, a member of the Alawite offshoot of Shiite Islam.
Claims by the group, including for past bombings, have been difficult to verify.
The head of the dissident Free Syrian Army in remarks published on Sunday charged that Al-Qaeda had links with the powerful airforce intelligence agency of the regime.