The claims about the 20 cases, which were made by an academic previously involved in advising the church on sexual abuse and how to respond to it, also came as a report suggested that Cardinal Keith O'Brien was summoned to Rome to answer charges of sexual impropriety as early as October last year.
O'Brien was forced to resign last month by Pope Benedict XVI, barely 36 hours after the Observer disclosed that three serving priests and one former priest were accusing him of "inappropriate acts" against them nearly 30 years ago.
While he made a dramatic admission last weekend that he was guilty of sexual misconduct throughout his career in the church, new questions about the handling of his case have now been raised by a report by the Catholic weekly, the Tablet, which claimed that he was called to Rome last year after a priest lodged an allegation with the Congregation for Bishops. A spokesperson for the Scottish Catholic church last said that he was unable to confirm the report as O'Brien is currently out of the country.
A separate report by the BBC, which claimed that bishops knew of as many as 20 allegations of child sex abuse by priests, was based on correspondence between senior clerics and Alan Draper, an expert in social work and lecturer at Dundee University who compiled a report for the church on how to deal with abuse.
After writing to Scotland's eight bishops to ask how much they knew, letters were sent to him reported to refer to 20 allegations of child abuse. Draper said the bishops rejected his suggestions that independent experts should investigate.
He remains scathing about the hierarchy's response to the report drawn up by him and a working party and last night called on the church to open up its files and records to an independent assessment.
"Certainly there's strong evidence to say some of the priests were out of control sexually, whether they be homosexual or heterosexual," he said. "The file should be made open to an independent group, preferably chaired by a judge."
In a response last night, the Catholic church said that it has had nationally agreed guidelines on the protection of children and vulnerable adults since 1999. It added: "All allegations are notified to the police. The church recognises that the statutory authorities are the responsible bodies for investigation."
The church said that Draper was involved at an early stage in the development of policies and procedures but was replaced "when others with greater competence were engaged".
"The number of annually reported incidents in Scotland have been small since we began to audit and have only very rarely involved a member of the clergy," it added.
The church also responded to the BBC's reporting on the case of a man who claims he was abused by a priest in the 90s, from the age of nine or 10 until his early teens.
"As soon as the complaint was reported, the police were informed, the priest concerned was removed from his parish and after they investigated the police passed a report to the fiscal, who took no further action," it added.
The church sent its file to the Vatican in July last year and is now awaiting a decision. The priest has not been in ministry or allowed to celebrate public masses or sacraments since he was removed from his parish.
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