Children in custodial and secure units are "not safe from physical or sexual abuse", an inquiry has found.
The investigation considered reports of abuse in secure children's homes, training centres and young offender institutes across the country.
From 2009-17, 1,070 incidents of sexual abuse were reported.
A former chief inspector of prisons described children in custody as "very vulnerable children in a very dangerous place".
The number of complaints has raised significant concerns due to the decline in the number of children held in these units, which fell from about 3,000 in 2008 to the current population which stands at below 900.
The independent inquiry said it remained the case that children in custody - some as young as nine - were among the most vulnerable in society.
Adult complainants were included in the report, detailing the abuse they suffered while they were held in secure units as children.
Prof Alexis Jay, chair of the inquiry, described the accounts "of non-recent child sexual abuse within custodial institutions [as] some of the worst cases this inquiry has heard".
During the inquiry it was alleged in February 2010 a member of staff at Vinney Green in Bristol told a female resident she had a "nice arse" and asked if she would "like to be part of a threesome".
A witness from Stanhope Castle approved school recounted 35 incidents of rape and sexual assault at the hands of four members of staff and a former pupil.
He said he was also choked unconscious several times during the abuse.
Among the seven recommendations to come out of the report are that the Department for Education and Youth Custody Service (YCS) should conduct a review of practice for placing children in secure units.
The panel has also advised that the Ministry of Justice, the Department for Education and YCS should share policy responsibility for managing and safeguarding children to ensure discipline is balanced with securing child welfare.