The "scale and severity" of physical abuse against young men, allegedly carried out by a former colleague of the Archbishop of Canterbury, was "horrific" a 1982 report found.
A series of accusations have been levelled against John Smyth, a former leader at the Iwerne Trust camps, which had close links with the Church of England.
It is where Justin Welby worked as a dormitory officer in the late 1970s, but he has insisted he was "completely unaware" of the allegations at the time.
They have come to light following a six-month Channel 4 News investigation into the prominent QC and part-time judge, who is now based in South Africa.
The Iwerne Trust, which oversaw the Christian camps, was made aware of the allegations after a young university student tried to commit suicide, Channel 4 News said.
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 they failed to tell the police 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".
Although not naming Mr Smyth, Hampshire Police have confirmed it is investigating "a senior figure at the Iwerne Trust".
Appealing for victims to come forward, a statement said: "We are investigating allegations of non-recent physical abuse involving a senior figure at the Iwerne Trust.
"We have contacted those victims whose information has been provided to us and we would encourage anyone else with any information about these events to contact our dedicated investigation team via 101, quoting Op Cubic."
When pressed about the allegations, Mr Smyth told the broadcaster: "I'm not talking about that."
A statement issued on behalf of Mr Welby (pictured) on Wednesday said that "although the Archbishop worked with him, he was not part of the inner circle of friends".
It added: "We recognise that many institutions failed catastrophically but the Church is meant to hold itself to a far, far higher standard and we have failed terribly.
"For that the Archbishop apologises unequivocally and unreservedly to all survivors."
Speaking on LBC Radio on Thursday, Mr Welby said he had been "completely unaware" of any allegations when he worked at the camp.
He said: "I was at that particular camp in the mid-70s. I was young then - 19 to 21 or 22. I never heard anything at all, at any point."
Speaking about Mr Smyth, the Archbishop added: "I wasn't a close friend of his. I wasn't in his inner circle or in the inner circle of the leadership of the camp, far from it."
Mr Welby said he was first informed of the alleged abuse in late 2013 or early 2014, by which time it had been reported to the police "as per the Church rules".
He added that he had only had fleeting contact with Mr Smyth since.
The Titus Trust, which took over some functions of the Iwerne Trust, said it was made aware of the "very grave" allegations in 2014 and informed police and the Charity Commission, but that they "should have been reported to the police when they first became known".
Public school Winchester College, which had connections with Mr Smyth, confirmed in a statement that it had carried out its own investigation into allegations about him.
The statement said "nothing was held back" in their 1982 inquiries - with house masters informed and many parents consulted. As a result Mr Smyth was asked never to return or contact any pupils.
It said no report was made to the police at the time, partly at the wish of the parents of the boys involved in the allegations.
The statement added that they are now in contact with the police and will assist further in any criminal investigation.
Copyright (c) Press Association Ltd. 2017, All Rights Reserved. Picture (c) Victoria Jones / PA Wire.