Pope compares child sex abuse to 'human sacrifice' at landmark Vatican summit

"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".

Francis said those who priests who prey 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."

On Saturday, the pope led those gathered in a penitential liturgy, saying: "We must say, like the prodigal son: 'Father, I have sinned'".

In a nod to those bishops -- particularly from Asia and Africa -- who have persisted in denying child sex abuse is a problem in their countries, he called on all present "to look honestly at the situation in our countries and our own actions".

'Enemy is within'

The meeting has been marked by soul-seeking and self-recrimination by the Roman Catholic Church, and horror stories from abuse victims.

The admission sparked an angry reaction from the international association ECA (Ending Clerical Abuse), which slammed the destruction of such documents "illegal" and called for an investigation.

The ongoing scandals have hit countries around the world, with recent cases affecting Chile, Germany and the US.

Those gathered heard testimonies from victims, one of whom was forced to have three abortions after being abused for years by a priest who beat her, while another said he had been molested more than 100 times.

"Engraved in my eyes, ears, nose, body and soul, are all the times he immobilised me, the child, with superhuman strength," said another woman, who described to the assembly how she was repeatedly raped aged 11 by a priest.

Marx, a liberal who has apologised to German clerical abuse victims, insisted there were "no alternatives to transparency", adding that attempts to cover-up scandals risked seriously undermining the Catholic Church's credibility.

Cardinal Blase Cupich of Chicago said new legal procedures were needed to deal with those either accused of abuse or of protecting alleged perpetrators, and insisted lay experts should be involved in every step. He said transparent new structures were needed to ease both the lodging of allegations and the removal of the guilty from office.

Telling the public about the number and type of investigations underway would help counter mistrust, the cardinals said.

The Vatican has in the past refused to hand over internal documents about abuse cases to police investigating paedophilia.

The Church had to "recognise that the enemy is within", Cardinal Jose Horacio Gomez said on Thursday.

"The damage caused is so deep, the pain inflicted is so profound, the consequences of the abuses that have taken place in the Church are so immense that we will never be able to say that we have done all that can be done," he 

said.

By AFP's Ella Ide