Inmates at Glen Parva Young Offender Institution do not feel safe, according to an official inspection report.
Nick Hardwick, the Chief Inspector of Prisons, said an unannounced inspection of the facility – which at the time held 659 men aged 18 to 21 – found a range of problems.
He set out his concerns in a report which was released today.
It said the inspectors found half of prisoners had felt unsafe at some time during their sentences and that assaults on prisoners and staff were rising.
Some prisoners committed offences in order to be sent to the segregation unit, because they felt safer there, the report said. Inspectors criticised the attitude of some members of staff who, they felt, accepted that poor behaviour by detainees was inevitable.
The prison was not doing enough to reduce availability of "legal high" drugs and too many inmates were being held in dirty conditions – including many sharing cells designed to hold single prisoners.
Mr Hardwick said: "Glen Parva is a concerning institution. Management can do much to improve things.
"There was some reassurance many of the problems at Glen Parva had been identified and there were plans in place to address them, which they had begun to implement before the inspection started.
"It is much too early to assess these changes."
The prison was urged to improve its efforts to reduce suicide and self-harming.
Two inmates killed themselves in 2013. Another took his own life this year.
Frances Crook, chief executive of the Howard League for Penal Reform, said: "The Government must take courageous action to take these young people out of such a toxic environment before more of them die."
The league released a statement from a Derbyshire mother whose son died at the prison.
Karen Revell said: "I and my family have been left devastated and heartbroken over the apparent suicide of my son Greg while in the care of Glen Parva.
"Our thoughts are with any other family this has happened to and we pray no other family is left as desolate as we are without our precious baby."
Michael Spurr, chief executive officer of the National Offender Management Service, said: "The challenges presented by the young men held at Glen Parva should not be underestimated and, on occasions, the prison has struggled to cope.
"The governor launched an improvement plan prior to this unannounced inspection and progress is being made.
"Safety is the governor's top priority and the institution is now providing a safe and decent regime."
The inspectors praised a number of areas of the prison's management, including the support for prisoners with disabilities, health care system, "innovative" substance misuse service, work and training opportunities for prisoners and "reasonable" post-release resettlement services.
