Amnesty International expressed concern that video footage, reportedly taken from the western Syrian province of Idlib, appears to show "a mass summary killing" of captured members of Syrian security forces. The rights group said it's believed that at least 28 of the men in custody died.
U.N. High Commissioner for Human Rights Navi Pillay said Friday it was difficult to verify what's depicted in the video without further investigation.
The allegations are that these were soldiers who were no longer combatants and therefore, at this point, it looks very (much) like a war crime," she said in a statement. "Another one."
Amnesty International said it wasn't able to confirm the identity of the armed groups that carried out the executions. No group has claimed responsibility.
Both sides to the conflict in Syria are suspected of committing war crimes. The U.N. Security Council hasn't been able to pass a resolution condemning Syria for the bloodshed. Russia and China, permanent members that hold veto power, say draft resolutions are one-sided.
Notable deaths of 2014 [PHOTOS]