The bodies lie on the muddy concrete bordering a small canal in Aleppo, many with their hands tied behind their back, each with a bullet to the head, their blood spilling into the stagnant water below.
At least 68 young men and boys were killed in what Syrian activists are describing as a massacre in the war-torn northern city of Aleppo.
Video of the horrific discovery – which is understood to have been revealed as flood waters receded along the Quiq River – was posted on YouTube, and comes as UN special envoy to Syria Lakhdar Brahimi was scheduled to address the United Nations Security Council in New York on the Syrian crisis.
The 129-kilometre river, which separates the Bustan Al-Qasr district from Ansari in the southwest of the city, originates in Turkey and flows southwest of Aleppo, traverses both regime and rebel-held areas.
A Free Syrian Army officer at the scene, Captain Abu Sada, told Agence-France Presse at least 68 bodies had been recovered and many more were still being dragged from the water, which is in a rebel-held area.
“Several sources in the city reported the total number of dead could reach to 80 since there are still bodies floating in the river,” the London-based Syrian Observatory for Human Rights said in a statement.
A senior government security source told AFP “terrorists” were responsible for the killing, which is the term President Bashar al-Assad uses to describe those fighting to over to overthrow his regime.
At least 700,000 Syrian refugees have been registered by the United Nations High Commissioner for Refugees since the 22-month conflict began, with human rights groups reporting a sharp rise in the number of people fleeing to Jordan and Lebanon in the last week.
US President Barak Obama announced on Tuesday an additional $US155 million in humanitarian aid for people inside Syria and Syrian refugees across the region, which followed the UK's announcement on Saturday of an increase in its Syria donation of 21 million pounds. However aid agencies say this will only meet a fraction of the need.
An estimated 60,000 people - civilians, government soldiers and rebel fighters - have been killed in the ongoing conflict, the UN estimates.