A top lawyer and Liberal Democrat peer today revealed that he had been frightened by techniques used to subdue child prisoners.
Lord Carlile of Berriew said he asked custody staff to use "control and restraint" methods on him as part of an independent inquiry into their use on offenders under the age of 18.
He said: "I found the techniques ranged between the broadly acceptable and the frankly unacceptable.
"The most unacceptable was not a technique which involved pain - it involved three members of staff placing themselves in martial arts challenging poses before me.
"The way in which they positioned themselves was supposed to de-escalate the situation and it made me a little bit frightened - and I don't frighten easily."
Lord Carlile said routine strip-searching of children in prison should end and called for the use of physical force to be severely restricted.
He said he had been "shocked" by the treatment of child offenders.
A child abuse inquiry would normally be triggered if children elsewhere were treated in the same way, he added.
The 100-page report disclosed reports that some staff would "bait" children into situations that would lead them to being restrained for the adult's sexual gratification.
Lord Carlile said: "This conclusion was derived from talking to young people.
"There are probably very, very few staff who do that and they would be condemned by the vast majority of staff for having the views they hold."
It was also the case that some young detainees would deliberately seek physical force to gratify their own sexual needs.
"This has to be treated with great delicacy," said Lord Carlile, noting that some child prisoners will have experienced previous sexual abuse.
"Among the experts working with me were an experienced psychiatrist and an experienced paediatrician, who confirmed that this is a real danger among a small part of the population."
The report, commissioned by the Howard League for Penal Reform, revealed that physical force was used against youngsters 15,512 times in a 21-month period in England and Wales.
Lord Carlile, a former MP who is also the Government's independent anti-terror watchdog, said responsibility for under-18s in custody should be taken away from the Prisons Minister and handed to the Children's Minister.
He said staff demonstrated three different restraint techniques on him, including a so-called distraction technique involving an upward jab to the nose.
None of the demonstrations drew blood, he added.
"I felt that I could not conduct this exercise without having the techniques administered on myself. I was a willing victim - I wasn't 'kicking off'.
"The response to pain, especially when one is angry, is for one to become agitated and that is in the background, I believe, of some of the tragic events, including the death of Gareth Myatt, which triggered this report."
Gareth, 15, who weighed just seven stone, died in April 2004 after being restrained by three members of staff at the privately run Rainsbrook secure training centre near Rugby.
Lord Carlile, who made 45 recommendations in all, said: "My team of expert advisers shared my shock at some of the practices we witnessed.
"If children in custody are expected to learn to behave well, they have to be treated well and the staff and various authorities have to set the very highest standards.
"The rule of law and protection of human rights should apply to all children equally, regardless of whether they are detained in custody or in the community."
The report called for:
* cuts in the use of strip searching by at least 50% and a ban on mechanical restraints, such as handcuffs;
* severe restrictions on the use of physical force, which should never be used to secure compliance or as a punishment;
* prison segregation units should never be used for children.
One young offenders' institution carried out 3,379 strip searches in 18 months, but it was unclear whether any contraband had been found, the report said.
When staff did discover items in other institutions, they tended to be tobacco rather than drugs or weapons.
Therefore, there was no convincing evidence that stripping children during searches helped with security, it went on.Reuse content