Pope Francis on Sunday compared the sexual abuse of children to human sacrifice as he addressed the Catholic Church's top bishops at the end of a landmark summit to tackle paedophilia.
"Our work has made us realise once again that the gravity of the scourge of the sexual abuse of minors is, and historically has been, a widespread phenomenon in all cultures and societies," he said.
"I am reminded of the cruel religious practice, once widespread in certain cultures, of sacrificing human beings – frequently children – in pagan rites," he added.
Francis was speaking after a four-day meeting which he had opened by calling for "concrete measures" on tackling priests and handing 114 senior bishops a roadmap to shape the debate on how to stop a global scandal.
"If in the Church there should emerge even a single case of abuse – which already in itself represents an atrocity – that case will be faced with the utmost seriousness".
The ongoing scandals have hit countries around the world, with recent cases affecting Australia, Chile, Germany and the US.
Francis said those who priests who pray on children are "tools of Satan".
"No explanations suffice for these abuses involving children," the Argentine pontiff said.
"The echo of the silent cry of the little ones who, instead of finding in them fathers and spiritual guides encountered tormentors, will shake hearts dulled by hypocrisy and by power.
"It is our duty to pay close heed to this silent, choked cry," he added.