Forces loyal to Syrian President Bashar al-Assad have been accused by opposition activists of a massacre in the town of Daraya, near Damascus.
More than 200 bodies have reportedly been found in the working-class suburb following an army assalt which ended days of shelling.
According to activists, most of the dead had been killed "execution-style" by troops in house-to-house raids, with gunshots to the head and chest from close range.
"Assad's army has committed a massacre in Daraya," said Abu Kinan, an activist in the town.
"In the last hour, 122 bodies were discovered and it appears that two dozen died from sniper fire and the rest were summarily executed by gunshots from close range," Abu Kinan told news agencies by telephone.
Video footage from capaigners showed what appear to be numerous bodies of young men side-by-side at the Abu Suleiman al-Darani mosque in Daraya, many with what looked like gunshot wounds to the head and chest.
However, it has been impossible thus far to independantly verify the accounts.
The official Syrian state news agency said: "Our heroic armed forces cleansed Daraya from remnants of armed terrorist groups who committed crimes against the sons of the town and scared them and sabotaged and destroyed public and private property."
The alleged massacre comes amid claims of over 440 deaths throughout Syria on Saturday, including dozens of civilians, in one of the bloodiest days of the uprising so far.
UN estimates put the total death toll from the conflict at over 18,000.