Children in a youth jail are being locked in their rooms for 23 hours a day, despite watchdogs previously branding it "unacceptable".
Oakhill secure training centre in Milton Keynes houses 46 boys aged between 12 and 17.
In a monitoring report into the facility by Ofsted, the Prison Inspectorate and the Care Quality Commission warns “widespread failings” are having a “significant impact” on the care and well-being of child inmates.
Children have spent approximately 19 hours per day on average locked in their rooms, increasing to 23 hours on some days, according to records published by the centre.

Inspectors have also raised concerns over the accuracy of the data, indicating the time the boys have spent in their rooms could be higher than what is being reported by the centre, the Independent reports.
It comes just 10 months after the same inspectors issued an urgent warning to another secure training centre in England after it emerged children were being locked up for 23-and-a-half hours a day.
Furthermore, it also came out that children at the centre in Rainsbrook, Rugby, were subjected to a "spartan" regime.
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In June, the government removed all 45 children living in that centre to other custodial settings.
The then-justice secretary Robert Buckland said he had “left with no choice” due to the “very serious failings” at Rainsbrook.
Campaigners have said the recent bombshell Oakhill report should be the “final straw” and that secure training centres be shut down to ensure children in trouble are “given the care and support they need".
Anna McMorrin MP, shadow minister for victims and youth justice, said there was an “alarming pattern of failure” across the youth justice system and accused ministers of “repeatedly failed to act on past warnings”.
She told the Independent: "It is time for the government to commission an independent review of youth custody, as Labour has called for, to get a grip on this spiralling crisis."
The new report also notes how temperatures in children’s living units and in other parts of Oakhill were “too high”, leading to an environment during the summer months that is “not conducive to positive care”.
The report states: "There was no means of cooling the children’s living units or staff administration areas. This makes living and working at the centre very uncomfortable at best."
Inspectors were told by children that activities were cancelled last minute - usually because there wasn't enough staff.
Furthermore, minimal staffing levels during July and August 2021 were not met
Staff told inspectors that morale was “very low” and that they did not feel supported by managers.
The report notes: “The way in which centre staff encourage children to develop positive behaviours and social skills is in disarray.”
Inspectors conclude that children’s day-to-day experiences are “very poor” and that “little progress has been made” since similar concerns were raised by inspectors in May 2021.
Andrew Neilson, director of campaigns at the Howard League for Penal Reform, said: “The distressing realities revealed in this inspection report echo what the Howard League has seen through its own legal work with children in custody during the pandemic and before, with boys locked in their cells for hours on end without fresh air or face-to-face education.
He added: "This report on Oakhill should be the final straw. It is time to close the secure training centres and ensure that boys and girls in trouble are given the care and support they need.”
A spokesperson for Oakhill told the Independent the safety of children was “paramount”.
They added: “Earlier this year, staff numbers at Oakhill were severely depleted by the impact of Covid-19 as significant numbers of staff were required, under prevailing regulations, to self-isolate at home.
“In these unprecedented circumstances, managers at Oakhill had to adopt a restricted operating regime, including remote learning for children from their rooms.”
They said that since the Ofsted visit, Oakhill’s operating regime for children had “improved” and that over the past month children had been able to spend on average 12 hours out of their rooms daily and education in classrooms had been “restored”.
The Mirror Online has attempted to contact Oakhill training centre.