A bishop might have put people at risk by ignoring grooming concerns to promote a priest and being friends with a paedophile, a review has found.
Bishop Robert Byrne undermined safety in the Hexham and Newcastle diocese, the Catholic Safeguarding Standards Agency (CSSA) said.
He was bishop from 2019 to 2022 but stepped down amid serious concerns over his handling of reports.
Bishop Byrne told the CSSA he supported keeping people safe.
The CSSA said overall the Roman Catholic diocese was meeting the "minimum standards" of guidelines and was ranked as having made "early progress".
But auditors heavily criticised the tenure of Bishop Byrne, in particular his promotion of Canon Michael McCoy to Dean of St Mary's Cathedral in Newcastle and the bishop's "inappropriate" friendship with Father Timothy Gardner, a priest convicted of child sex offences.
The CSSA said the bishop's "poor leadership" had "undermined" the safeguarding work of others "to the degree that people were put at potential risk".
Auditors said concerns were raised about Canon McCoy in 1996, 2007 and 2010 owing to his "inappropriate behaviour with young people including the offer of foreign holidays and providing alcohol to them despite being underage".
Yet, despite having a "significant history of safeguarding concerns" which the bishop had been told about multiple times, Canon McCoy was still promoted.
The CSSA said Canon McCoy, who killed himself in 2021 after an investigation into historical allegations was launched, displayed a "clear pattern of grooming behaviour over the years" and there was an "abundance of warning signals" with the diocese missing opportunities to "prevent or ameliorate harm".
By appointing Canon McCoy to an "important diocesan role", the bishop either showed a "lack of understanding" of safeguarding or a "complete disregard for it", the review concluded.
In relation to Gardner, who was given a suspended prison sentence in 2014 for possessing hundreds of indecent images of children, the CSSA said multiple people reported a "close friendship" between Bishop Byrne and the priest with the pair frequently socialising, including at church properties.
The bishop tried to get him work in the diocese's archives in 2019 and for an overseas charity in 2021 but both were blocked because of Gardner's criminal record, the agency said.
The review found the men's association was "inappropriate" and allowed Gardner "unrestricted access" to a number of diocesan premises which had "presented a serious safeguarding risk".
Steve Ashley, of the CSSA, told the BBC that there was "always a risk of offending" if a bishop gave "visible support" to a convicted sex offender and allowed him "free access" under "the title of being a priest".
The bishop told the review he was only ever offering "pastoral care" to a friend of more than 30 years but the auditors found "no evidence to support" that claim.
The CSSA said Bishop Byrne would make "key decisions without any consideration to the wider safeguarding context" especially when a "friend or associate was involved".
Safeguarding workers in the diocese resigned in protest after the bishop ignored their concerns and his actions were likely to have "severely damaged" trust between the church and survivors of sexual abuse, the CSSA said.
"There was a lack of clear and unambiguous support from Bishop Byrne for the Church's position of zero tolerance of abuse," the CSSA said.
Bishop Byrne has been unavailable for comment but told the review he shared the CSSA's commitment to safeguarding.
Auditors made 12 recommendations to the diocese, which covers Northumberland, County Durham, Darlington, Stockton and Hartlepool, and 10 to the Church across England and Wales.
'Work to be done'
The Archbishop of Liverpool Malcolm McMahon, who has been overseeing the diocese until a new bishop is appointed, said he commissioned the review to "address the issues in a very direct way" and accepted its "scathing" findings.
He said the church apologised "many times" to survivors of abuse but "words had to be followed by actions".
The archbishop said one of the issues was many people within the Church only had an "advisory role" and "ultimately if senior people do not take that advice that's when things go wrong".
He said "extensive steps" had been taken to "stamp out" a "culture" that had not taken safeguarding seriously enough.
The archbishop also said he could "confidently" say the diocese was a "safe place" today, although there was "still work to be done" with an "endless cycle of training and checking".
More work was needed in regard to the church's care for survivors and including them in the future of safeguarding, he added.