Children have been arming themselves with weapons at a young offenders institution with the highest violence rates of any prison in England and Wales, according to a report.

Inspectors found there had been 105 assaults among young inmates – 31 of which were so serious they resulted in hospital admission – and 82 on staff over just six months at HMYOI Werrington.

The prison was judged to be overly reliant on “keep-apart” lists – used to separate groups or individuals at risk of becoming violent if allowed to mix.

An “astonishing” 263 “keep-aparts” were in place for just 66 children, Her Majesty’s Inspectorate of Prisons (HMIP) found.

Charlie Taylor, HM Chief Inspector of Prisons, said: “This ineffective and harmful arrangement was, in effect, a reactive process of risk avoidance, rather than risk management, and had come to totally dominate life in Werrington.”

Records indicated that nearly 400 weapons had been found over the 12 months prior to the inspection, according to HMIP.

Rates of violence over the six months to January stood at 23 assaults for every 10 children, representing the highest of all prisons in England and Wales, the report found.

The conditions in the prison were also “severely detrimental” to education, which was provided not on the basis of needs but according to which children could mix with one another, inspectors said.

Many were unable to enrol on their preferred course and instead took ones which did not engage them as a result, according to HMIP.

The findings are the latest in a series of critical reports on the safety of the prison.

In 2019, the institution, near Stoke-on-Trent in Staffordshire, was found by inspectors to have become less safe than it was the previous year.

HMIP added in its 2022 report that although standards had dropped from “good” to “reasonably good” there were some encouraging signs, including in the institution’s health services, which it described as “child-centred”.

But the inspection, which was unannounced and took place in January, was “disappointing” overall, HMIP said.

Mr Taylor added: “We were left with the sense that Werrington had lost its way and needed to rediscover a sense of purpose.”

He added: “The governor had set out a series of priorities for the establishment, but it was clear to us that more needed to be done to ensure staff were fully committed to these priorities and that plans were delivered.”

A Youth Custody Service spokesperson said: “We have put in place immediate measures to address the concerns of inspectors, including reducing the number of children at Werrington, introducing a new conflict resolution team, expanding purposeful activity and putting staff through extra training on tackling violence.”

The inspection report comes as the Ministry of Justice (MoJ) announced £300 million will be put towards tackling youth offending and cutting crime, describing this as the biggest funding package in a generation.

The department said thousands of “troubled children and teenagers teetering on the edge of crime will be put back on the right track” thanks to the investment over the next three years, with a new scheme to “catch” and help them turn their life around.

Up to 20,000 more children will be helped and for the first time councils will be given cash specifically to “intervene early with teenagers displaying signs such as poor school attendance, troubles at home, and a history of substance abuse which are known to be factors which often drive young people into crime – so they can steer them away from law-breaking before an offence is even committed”, the MoJ said.

Around 80% of prolific adult offenders begin committing crimes as children.