Activists say clashes between troops loyal to Syria's President Bashar al-Assad and armed rebels in the central city of Rastan have left at least 23 Syrian soldiers dead and dozens wounded.
No independent confirmation was available of the report on May 14 by the Britain-based Syrian Observatory for Human Rights.
The pro-opposition group said reports indicated that three troop carriers were destroyed in the clashes.
Earlier, opposition sources said nine people were killed in heavy army shelling of Rastan.
In Brussels, meanwhile, European Union foreign ministers have agreed to impose more sanctions against the Assad regime.
The new sanctions, to take effect on May 15, mean 129 people and 43 firms or utilities are now targeted by an assets freeze and travel ban.
The EU has imposed numerous rounds of sanctions targeting the Syrian government in a bid to halt the 14-month-old conflict.
Based on reporting by AFP and Reuters