Pope Francis has revealed that "reliable data" collected by the Vatican suggests that one in every 50 members of the Catholic clergy is a paedophile.
Speaking in an interview with La Repubblica, the Pope said his advisers had tried to "reassure" him that paedophilia within the Church was "at the level of 2%".
He pledged that he would drive away the "leprosy" of child abuse that was infecting the "house" of Catholicism.
"I find this state of affairs intolerable," he said.
Pope Francis said his advisers at the Vatican had given him the 2% estimate, which included "priests, bishops and cardinals".
He also warned of much greater figures for people who were aware of the existence of abuse – sometimes within their own families – but who stayed silent because of corruption or fear.
His comments came a week after the Pope met six victims of clerical paedophilia to apologise for their abuse at the hands of priests.
The meeting, with six British, Irish and German Catholics, was designed to acknowledge the gravity of the Church's guilt and complicity.
Despite Pope Francis's popularity, there has been criticism of him for failing to take a high-profile stand against the global paedophilia scandal.
Meanwhile, the Archbishop of Canterbury has admitted that an inquiry into allegations of child sex abuse at the heart of the establishment is likely to turn up fresh claims about the Church of England.
The Most Rev Justin Welby said it was something he dealt with daily and it was becoming clearer that "for many, many years things were not dealt with as they should have been".
Abuse survivors must now be shown justice and the Church must be "absolutely transparent" every step of the way, he told BBC One's Andrew Marr Show.
Asked if he was braced for the inquiry to uncover "bad stories", Archbishop Welby replied: "I would love to say there weren't, but I expect there are. There are in almost every institution in this land.
"And we must show justice to survivors of abuse.
"And we must be absolutely transparent in every possible way and we have to keep saying how utterly devastated we are with the terrible things that were done in the past and how sorry we are."