A boy at a young offenders institute was left to lie on a mattress on the floor of a “filthy” cell for more than 22 hours a day, a report has revealed.
The chief inspector of prisons in England and Wales, Peter Clarke, said a practice of separating children from their peers at YOIs amounted to “harmful solitary confinement”.
He said the policy had “fundamental flaws” and was a risk to mental health.
The government said it would be making “immediate changes”.
Inspectors looked at five YOIs, holding about 600 men and boys aged 15 to 18 – Cookham Wood in Kent; Feltham A in west London; Parc in South Wales; Werrington in Staffordshire, and Wetherby and Keppel in West Yorkshire.
Mr Clarke said 57 offenders had been separated and “in the worst cases children left their cells for just 15 minutes a day”.
His report, after inspections in May and June 2019, found “multiple and widespread failings”, although some areas of better practice were identified, particularly at Parc.
It said there were occasions when it was in a child’s best interests to be separated for the risk they posed to others, or for their own protection. But staff should still aim to ensure they have daily activities and work to reintroduce a normal regime.
Mr Clarke found eight children had spent a combined total of 373 days in separation while waiting to be taken to a secure hospital for treatment for mental health conditions.
He said nearly all those separated spent long periods in cells “without any meaningful human interaction”.
This included the case of the boy left on the mattress, which took place at Feltham A, where he had been “in crisis” and on a “constant watch”.
Some were “unable to access the very basics of everyday life, including a daily shower and telephone call”, Mr Clarke added.
He recommended an “entirely new approach”.
Justice minister Wendy Morton said: “It is difficult to read this report and not conclude that we are failing some of the children in our care. That is completely unacceptable and I am determined it will not continue.”
She said separation can be “necessary” but there was “no excuse for some of the practices highlighted in this report and I have asked my officials to urgently set out the steps we need to take to stop them happening”.