Survivors of the massacre in the Syrian town of Houla say that the vast majority of people were killed in two bouts of summary executions, according to UN rights spokesman Rupert Colville.
They allege that the executions were carried out by the pro-government Shabbiya militia in the nearby village of Taldaou.
However, Mr Colville stressed that the UN is still in the early stages of its investigation. He confirmed that less than 20 of the 108 confirmed victims died from artillery or tank fire.
He also said that 49 children and 34 women were among the victims.