BEIRUT, Lebanon — Dozens of bodies, possibly more than 200, were found Saturday in a town outside Damascus, raising the specter of a massacre by Syrian troops as bad as any atrocity committed since the Syrian uprising began nearly 18 months ago.

The circumstances and number of deaths in the town, a suburb named Daraya, could not be confirmed independently, and the reported death toll varied.

The Syrian Observatory for Human Rights, a Britain-based group with a network of activists inside Syria, said early Saturday that there were 40 to 50 bodies, while another activist organization, the Local Coordination Committees, raised the toll to more than 200 that night.

The latter group said its activists found one mass body dump after another. They posted two videos showing what they said were different groups of victims; in one a series of charred bodies could be seen wrapped in blankets; in another, a far larger group of bodies — more than 150, according to the video’s narrator — had been lined up together in a dark area of what was said to be a local mosque.