Pope Francis has said 2 per cent of the Roman Catholic clergy worldwide, the equivalent of 8000 members, are paedophiles.
The figure was revealed as the Archbishop of Canterbury separately admitted he expects more sex scandals to emerge from within the Anglican Church.
The Pope described child sex abusers as a "leprosy" within the Catholic Church and said the offenders include "priests and even bishops and cardinals".
In an interview with La Repubblica newspaper in Italy, the Pontiff cited his aides as saying that "the level of paedophilia in the Church is at 2 per cent". As the Catholic clergy numbers 414,000, it would mean more than 8000 priests fall into this category. Estimates of the prevalence of paedophilia in the wider population range from a fraction of 1 per cent to 4 per cent.
In an interview on the BBC's Andrew Marr Show yesterday, the Archbishop of Canterbury, the Most Rev Justin Welby, said it was becoming clearer that paedophilia had not been properly addressed within Anglicanism and disclosed that he deals with the issue daily.
Asked if he was braced for the child abuse inquiry led by Baroness Butler-Sloss to uncover "bad stories", the Archbishop replied:
"I would love to say there weren't, but I expect there are. There are in almost every institution in this land."
The Pope also promised to find "solutions" to the issue of priestly celibacy. Asked whether priests might one day be allowed to marry, he said celibacy was instituted "900 years after Our Lord's death" and clerics could marry in some Eastern churches under Vatican tutelage.
The Vatican later tried to backtrack on the interview.
Father Federico Lombardi, its main spokesman, said: "This is not at all an interview in the normal sense of the word." But he declined to say in which parts of the interview the Pope had been misquoted or misrepresented.