A former bishop has been criticised for unsatisfactory responses to child abuse allegations and risky behaviour of priests.
A watchdog review of the Diocese of Clogher, which straddles the border between the Irish Republic and Northern Ireland, found opportunities to prevent attacks in the past were consistently missed when concerns were raised.
The National Board for Safeguarding Children in the Catholic Church in Ireland said, however, that a line should be drawn between how the diocese used to do its business and the rules in place today.
Bishop Joseph Duffy led the diocese for about 30 years until his retirement in 2010.
The report into Clogher is one of seven being released today by the watchdog.
Bishop Liam McDaid was ordained as Bishop of Clogher on 25th July 2010.
Ian Elliot, head of the Catholic church watchdog, noted an "unacceptable delay" in removing a priest from ministry after a credible child abuse allegation and another case where a priest suspected of multiple abuse was not removed from ministry but transferred to another parish and eventually sent overseas for therapy.
Ultimately he was extradited back to Ireland but died before he could face trial.
"In a number of cases, allegations emerged against priests following their death making it impossible for any investigation to take place," the report found.
"The impression formed by the reviewers of past practice was that the response to abuse concerns was often unsatisfactory and that risky behaviour was not addressed as strongly as it should have been."
Elsewhere, the review - part of a nationwide audit to ensure bishops follow adequate child protection rules - noted that 13 priests of the diocese have faced allegations since 1975, one is classed as either in ministry or retired and two clerics have been convicted.
Clogher has 37 parishes with 73 priests across Monaghan, most of county Fermanagh, and parts of Tyrone, Donegal, Louth and Cavan and it also includes the Lough Derg pilgrimage site.
Between 1975 and November 2012 in Clogher 23 allegations of abuse were reported to gardai in the Republic and 22 to the health service.
Seven of the priests facing allegations were dead.
One priest in the diocese was known to have faced abuse allegations from a previous ministry, the report also found.
In a separate report on the Diocese of Galway, Kilmacduagh and Kilfenora the name of the former controversial bishop, Eamon Casey, cropped up for not removing a priest from ministry when an allegation was made.
The disgraced cleric fled Ireland to a mission in Ecuador in 1992 when it emerged he had a secret love-child with American woman Annie Murphy while he was Bishop of Kerry in 1974.
He returned to the west of Ireland from ministry in the UK in 2006 after he was notified of an abuse allegation.
His successor, the late James McLoughlin, removed the accused priest from ministry in 1995. The priest has since died.
Seperately, McLoughlin was also criticised for not properly dealing with another complaint against one of his former clergy.
The diocese has a total of 63 priests in 39 parishes across the west of Ireland, including three priests in ministry who had allegations made against them over the last four decades.
Fourteen priests had allegations made against them from January 1975 to January 2013. One has been convicted.
The watchdog found that historically there had been delays in notifying the gardai and health chiefs of accusations during the 1990s and early 2000, but more recently there is very prompt reporting of all cases.
While prompt action was taken to remove men from ministry in all cases where credible allegations were made, the lack of written records was criticised.
The diocese was given seven recommendations to bring it up to standard, including reviewing all cases of living priests who are out of ministry.