The Church of England has been strongly criticised over its handling of serious abuse allegations against the late John Smyth.
An independent review led by Keith Makin found that Smyth had perpetrated "prolific and abhorrent" abuse over decades and that the response of the Church of England "amounted to a cover-up".
Makin said that "words cannot adequately describe the horror of what transpired".
"Many of the victims who took the brave decision to speak to us about what they experienced have carried this abuse silently for more than 40 years," he said.
"Despite the efforts of some individuals to bring the abuse to the attention of authorities, the responses by the Church of England and others were wholly ineffective and amounted to a cover-up."
He said that lessons must be learned from the review and that the Church of England must "implement robust safeguarding procedures across their organisations that are governed independently".
"This has been a long process but a necessary one to uncover the extent of John Smyth's despicable behaviour and how the Church reacted to it," he continued.
"I would like to sincerely thank the victims for their courage, grace and dignity and I would like to remind everyone reporting on this review about their right to anonymity and privacy."
The Church of England's Lead Safeguarding Bishop, Joanne Grenfell, and National Director of Safeguarding, Alexander Kubeyinje, apologised for Smyth's abuse and the Church's handling of the allegations.
"We are deeply sorry for the horrific abuse inflicted by the late John Smyth and its lifelong effects, already spanning more than 40 years," they said.
"The review concludes that Smyth is arguably the most prolific serial abuser to be associated with the Church of England.
"We know that no words can undo the damage done to people's lives both by him and by the failure of individuals in the Church and other institutions to respond well.
"We are also aware that the time the review has taken, which the reviewer addresses, as well as the details now in the public domain have been retraumatising for survivors."
They said they were "appalled" by comments highlighted in the review that were made by late cleric, David Fletcher, who was aware of the abuse in the 1980s and was quoted as saying, "I thought it would do the work of God immense damage if this were public."
"We are appalled that any clergy person could believe that covering up abuse was justified in the name of the Gospel, which is about proclaiming Good News to the poor and healing the broken hearted," Grenfell and Kubeyinje stated.
"It was wrong for a seemingly privileged group from an elite background to decide that the needs of victims should be set aside, and that Smyth's abuse should not therefore be brought to light.
"Every member of the Church is responsible for a culture in which victims are heard, responded to well, and put first: there is never a place for covering up abuse."
They said they would "fully support" any international investigation into Smyth's abuse after the report criticised Church officers for doing nothing to prevent Smyth from moving to Zimbabwe where the abuse continued and a boy was found dead in a swimming pool of one of his camps.
"We apologise unreservedly that the needs of the victims were not at the forefront in terms of thinking and planning and the response was not trauma informed," said Grenfell and Kubeyinje.
"We will continue to learn lessons about responding well which is reflected in our revised guidance and survivor engagement framework.
"We welcome all the recommendations and will consider them now in detail, noting work already underway. We wholeheartedly endorse the reviewer's emphasis that safeguarding must be everyone's responsibility in the Church, working closely with safeguarding professionals."
The Archbishop of Canterbury, Justin Welby, apologised for failing to ensure the allegations against Smyth were properly investigated after becoming aware of them in 2013, and for delaying in meeting victims.
"I am deeply sorry that this abuse happened. I am so sorry that in places where these young men, and boys, should have felt safe and where they should have experienced God's love for them, they were subjected to physical, sexual, psychological and spiritual abuse," he said.
"I am sorry that concealment by many people who were fully aware of the abuse over many years meant that John Smyth was able to abuse overseas and died before he ever faced justice. The report rightly condemns that behaviour.
"I had no idea or suspicion of this abuse before 2013.
"Nevertheless the review is clear that I personally failed to ensure that after disclosure in 2013 the awful tragedy was energetically investigated. Since that time the way in which the Church of England engages with victims and survivors has changed beyond recognition. Checks and balances introduced seek to ensure that the same could not happen today.
"I repeat my apology contained in the review, that I did not meet quickly with victims after the full horror of the abuse was revealed by Channel 4 in 2017. As the report says, no Archbishop can meet with everyone but I promised to see them and failed until 2020. This was wrong."
