Fierce clashes between Syrian government forces and opposition fighters have left at least 23 soldiers killed in the central Syrian city of Rastan, activists say.
Dozens more were wounded in Monday's violence, the UK-based Syrian Observatory for Human Rights said.
Opposition sources also said the army had shelled the town, which they say has been under rebel control since January. Nine people were reportedly killed in the bombardment.
"Shells and rockets have been hitting the town since 3am (12:00 GMT) at a rate of one a minute. Rastan has been destroyed," a member of the opposition Free Syrian Army in Rastan who declined to be named told Reuters news agency by satellite phone.
Al Jazeera's Rula Amin, reporting from Beirut in neighbouring Lebanon, said three armoured vehicles carrying government troops had been attacked as they were heading to Rastan, in Homs province.
"Rastan is a strategic town and a stronghold of the Free Syrian Army," she said. "Many defectors from the army comes from Rastan."
Syrian authorities say more than 2,500 members of the security forces have been killed since the uprising began in March last year. Opposition activists say more than 9,000 people have been killed.
Monday's violence further undermines a UN-backed peace plan that is supposed to bring an end to Syria's deadly crisis.
A ceasefire that was supposed to begin on April 12 has had only a limited effect, throwing into doubt the rest of the plan that calls for talks between President Bashar al-Assad's government and those seeking to end his rule.
In-depth coverage of escalating violence across Syria
Part of the plan includes the deployment in flashpoint areas of around 300 UN military observers. By Sunday,189 observers were on the ground, and several more arrived on Monday.
In the latest effort to isolate Syria internationally, European Union foreign ministers agreed fresh sanctions against the country on Monday, the 15th round so far to protest against the repression of dissidents.
An EU statement issued at a meeting of ministers said they adopted "sanctions against the Syrian regime" but gave no details.
An EU diplomat confirmed, however, that the ministers agreed to impose an assets freeze and visa ban on two firms and three people believed to provide funding for the regime.
Syria-linked violence has spilled across the border into Lebanon, with five people killed since Saturday during clashes in the northern port city of Tripoli, according to officials.
Gunbattles erupted on Saturday between residents loyal to Syrian President Bashar al-Assad and those supportive of the Syrian opposition.
Fighting flared in Tripoli again on Monday, leaving two people dead and nine wounded, a security official told the AFP news agency.