The Bishop of Guildford has said he was one of 22 young men allegedly abused by a former colleague of the Archbishop of Canterbury.
Andrew Watson said he endured a "violent, excruciating and shocking" beating at the hands of John Smyth QC at a Christian camp in the late 1970s and early 1980s.
Accusations were levelled against Mr Smyth last week following a Channel 4 News investigation into his activities as a former leader at the Iwerne Trust camps, which had close links with the Church of England.
Other victims have accused Justin Welby of failing to expose the abuse and urged him to reveal how much he knew about the allegations.
Mr Welby worked as a dormitory officer on Iwerne Trust camps in the late 1970s but has insisted he was "completely unaware" of the allegations at the time and was not a "close friend" of Mr Smyth.
But in an open letter published in the Daily Telegraph, one alleged victim suggested Mr Welby was an "observer" of the abuse who "knew but never reported appropriately".
The letter, endorsed by seven other alleged victims, says: " And here's the difficulty about being an observer. You have to ask yourself, 'I knew about John Smyth. I become aware about some of the things that this abuser did, I have 'observed' them.
"'Can I look myself in the mirror and honestly say that I did everything I could to report to the correct authority all the things that I knew?
"'Did I give the people who might bring the abuser to justice every scrap of information that they might need? And, if I didn't, then thinking very carefully about this - whose side have I been on, all this time? The side of the victims. Or the side of the abuser?'."
It led to a report being complied in 1982, which states that Mr Smyth is believed to have beaten 22 young men and that despite this, police were not told about the abuse.
Channel 4 News said the report states: "The scale and severity of the practice was horrific. The other eight received about 14,000 strokes - two of them having some 8,000 strokes over the three years."
The report also described the beatings endured by the youngsters as "technically all criminal offences".
Bishop Watson said he was " one of the survivors of John Smyth's appalling activities".
He said: "I was drawn into the Smyth circle, as they were, and the beating I endured in the infamous garden shed was violent, excruciating and shocking; but it was thankfully a one-off experience never to be repeated.
"A while later one of my friends attempted suicide on the eve of another session in the shed (a story movingly told in the Channel 4 report), and at that point I and a friend shared our story.
"I have been in contact with the Hampshire police over the weekend, and it would not be appropriate to say much more at this time, except that my profoundest prayers are with all those affected by this, and my heartfelt desire is that lessons might be learnt so this never happens again."
The bishop added: "I am grateful to the Archbishop of Canterbury for his apology to survivors on behalf of the Church, and don't begin to believe that he knew anything of Smyth's violent activities until his office was informed in 2013."
The Iwerne Trust was made aware of the allegations after a young university student tried to commit suicide, Channel 4 News said.
Mr Smyth, a prominent QC and part-time judge now based in South Africa, refused to comment when approached by the broadcaster, saying: "I'm not talking about that."
Hampshire Police has confirmed it is investigating "a senior figure at the Iwerne Trust".