Syrian activists say at least 65 bodies, some of them with their hands tied behind their back, have been found on a river bank in the northern city of Aleppo.

The head of the Britain-based Observatory for Human Rights Rami Abdul-Rahman said the bodies were discovered on Tuesday in the city's contested district of al-Bustan al-Qasr.

All of the dead were men. Abdul-Rahman said it was not clear who was behind the killings, when they occurred or who the dead were.

The Local Coordination Committees activist group put the number of bodies found at 80.

Video streamed live on Bambuser showed rows of bodies wrapped in blue shrouds, lined up in what was described as a schoolyard.

The video was posted by a regular contributor of content to the Bambuser site, who is part of the Sham News Network activist group with which The Associated Press has regular contact.

Sham News Network is a loosely organised anti-Assad group based in and out of Syria which posts video and still images of anti-government protests on the internet.

They claim they do not have any connection to Syrian opposition parties or any other states.

The content of the footage was consistent with other opposition sources reporting the incident.