The Church of England "colluded" with and helped to hide the long-term sexual abuse of young men by one its bishops rather than help his victims, the Archbishop of Canterbury has said.
The Most Rev Justin Welby's statement came as the Church published Abuse Of Faith, an independent review of how it handled the case of Peter Ball, the former Bishop of Lewes who was jailed for 32 months at the Old Bailey in 2015 after pleading guilty to a string of historical offences, including two counts of indecent assault.
The review, chaired by Dame Moira Gibb, found that "Ball's conduct has caused serious and enduring damage to the lives of many men".
It stated: "Peter Ball betrayed his Church and abused individual followers of that Church.
"The Church at its most senior levels and over many years supported him unwisely and displayed little care for his victims.
"Much of what we have described took place in different times and should be viewed from that perspective.
"But such perverse and sustained abuse by a senior figure in the Church and the Church's failure to safeguard so many boys and young men still casts a long shadow."
During his time as bishop, Ball hand-picked 18 vulnerable victims to commit acts of "debasement" in the name of religion, such as praying naked at the altar and encouraging them to submit to beatings, his trial heard.
The Archbishop described the report as "harrowing reading", adding: "The Church colluded and concealed rather than seeking to help those who were brave enough to come forward.
"This is inexcusable and shocking behaviour and, although Dame Moira notes that most of the events took place many years ago, and does not think that the Church now would conduct itself in the ways described, we can never be complacent; we must learn lessons."
He restated his "unreserved apology" to the victims who had been brave enough to come forward, adding: "There are no excuses whatsoever for what took place and the systematic abuse of trust perpetrated by Peter Ball over the decades."
There is criticism in the review of Lord Carey, who was the Archbishop of Canterbury at the time, and senior figures in the Church, saying that their Church was "most interested in protecting itself".
The review states that Lambeth Palace's actions, especially in failing to pass on six letters of allegations to the police, while giving them one which was of "least concern" - "must give rise to a perception of deliberate concealment."
The review points out that the Church's management of those seven letters, containing allegations against Ball, is perhaps "its greatest failure in these events."
It states: "The letters came from a range of families and individuals quite independently of each other. They raised concerns which were all either indirectly or precisely suggestive of sexual impropriety, or worse, by Ball.
"These were not people who were at war with the Church or had any axe to grind. In fact, some of the correspondents go to great lengths to try to avoid rancour and find a constructive way forward."
The report found that Lord Carey was significantly involved in the way the Church treated victim Neil Todd in 1992-1993.
Despite years of abuse in Sussex, Ball was able to leave the diocese in 1992 to take up his post as Bishop of Gloucester.
A year later, the then 16 year-old trainee monk Neil Todd prompted a police investigation which led to Ball's resignation from the clergy.
Ball escaped with a police caution in 1993 for a single act of gross indecency against Mr Todd who persisted to be haunted by his treatment and took his own life in 2012.
Ball had an identical twin brother called Michael who was also a bishop. Lord Carey described the paedophile bishop as "basically innocent" and said he had a "very high" regard for him in a September 1993 letter to Bishop Michael.
The review, which said Lord Carey had played a leading role in enabling Ball to return to ministry, described this comment as "alarming".
It added: "Ball was basically guilty and had admitted that. Lord Carey was also aware that the Church had received further allegations of potentially criminal actions by Ball."
Ball's trial at the Old Bailey heard that a string of senior establishment figures had written letters in support of him while the police were investigating allegations of abuse.
Following a caution for gross indecency in 1993, Ball resigned and lived in a rented cottage on the Prince of Wales's Duchy of Cornwall estate.
He was not prosecuted for more than 20 years.
Ball tried to exploit his high-profile connections in order to bolster his position with senior church officials, especially Lord Carey.
The review adds: "We have received all the relevant material including the correspondence passing between the Prince of Wales and Ball held by the Church and found no evidence that the Prince of Wales or any other member of the Royal Family sought to intervene at any point in order to protect or promote Ball."