At least 25 people, including four children, were killed Thursday in multiple Syrian government air strikes on a town outside Damascus, a monitor said.
The Syrian Observatory for Human Rights said the deaths came in strikes on Irbin, just east of the capital, and that dozens more people had been wounded.
The toll was expected to rise further, the Britain-based group said, because a number of the injured were in serious condition.
Irbin is under opposition control and lies in the Eastern Ghouta region outside Damascus, which is a key rebel stronghold.
The region has come under increasing regime fire in recent months as the army steps up a campaign to retake territory around the capital from which rebels launch missiles at Damascus neighbourhoods.
More than 180,000 people have been killed in Syria since the uprising began in March 2011.