Chief Inspector of Prisons Nick Hardwick criticised Brinsford YOI, which holds 18- to 21-year-olds, for high levels of violence and drug use, poor security and “squalid” conditions.
Hardwick said the conditions were the worst he has seen in a prison during his four-year tenure as chief inspector for England and Wales.
The findings prompted the Howard League for Penal Reform to call for the immediate closure of the “unsafe, ineffective and violent” establishment.
The inspection report reveals that services to assess the individual risk and needs of the young people held there and offer them support in their early days at the establishment were poor.
Support on offer to young people in crisis was also found to be poor.
There were also a significant number of cells that had window panes missing and were “not fit for occupation”.
During the working day, 44 per cent of prisoners were locked up doing nothing and the amount of time out of cell for some young people was found to be very poor.
At its last inspection in 2012, inspectors criticised safety, the quality of the environment and the prison’s disappointing approach to resettlement.
Hardwick said Brinsford had “deteriorated markedly in almost all respects” since then.
“When we spoke to staff and managers they were aware of the problems but seemed overwhelmed, and they lacked a plan or the determination to begin to get to grips with what needed doing,” Hardwick said.
“We found so much wrong with Brinsford that it is going to take time to improve, but stronger leadership and capability from managers, along with a better approach and greater professionalism from staff, would be a start.”
Hardwick said that a new governor appointed shortly after the inspection, which took place in November 2013, has made a “vigorous start” on making the necessary improvements, but added he still has very serious concerns about the prison.
Michael Spurr, chief executive of the National Offender Management Service (NOMS), said immediate action was taken to improve the prison following the inspection.
“A new governor was appointed and urgent work was done to improve safety, ensure decency and increase activity,” he said.
“The prison is now clean, safe, ordered and is operating to an acceptable standard.
“There is more to do to ensure this rapid progress is maintained and embedded, but the governor has a clear strategy in place and has the full support of his staff.
“I am confident that when inspectors return they will see a much improved establishment."
However campaigners have called for the YOI to be closed.
Frances Crook, chief executive of the Howard League for Penal Reform, said: “Rather than locking up teenagers in squalid conditions, letting some out of their cells for just 10 minutes a day, the government needs to start to reconsider its policy of wasting public funds and young people’s lives behind bars," she said.
“This report should also be a wake-up call for magistrates who need to stop sending teenagers to dangerous and failing institutions like Brinsford and should instead make use of robust and effective community sentences run by probation services and available in their local areas.”
Deborah Coles, co-director of campaign group Inquest, said it was appalling that recommendations made following previous inspections had not been acted on.
“How can we hold the state to account when it allows the prison service to ignore its official watchdog?” she said.