British prisons are holding child inmates in solitary confinement in an alleged breach of UN torture rules and British law, The Independent has found. Lawyers in one case have launched legal action against the Government in the High Court.

More than a dozen examples uncovered by The Independent include a teenage prisoner with a serious mental health condition who, it is claimed, was placed in solitary confinement inside a number of different British jails during a period of six months, causing him considerable distress and psychological damage.

Prison inspection reports suggest some children have been driven to self-harm due to the severe emotional distress of solitary confinement.

MPs have called for an urgent Government investigation into the findings, which may breach the UN Convention Against Torture and the UN Convention on the Rights of the Child by amounting to "inhuman and degrading treatment".

Tim Farron, leader of the Liberal Democrats, said: “These are incredible allegations that fly in the face of Britain’s obligations both domestically, at European level and internationally. The use of solitary confinement should be kept to a bare minimum regardless of age but is incomprehensible for juveniles.”

The High Court legal challenge is an application for a judicial review concerning a boy who, it is claimed, is currently being held in solitary confinement. The Independent has agreed not to publish further details. If the case is granted, it would lead to a case against the Government.

Article 16 of the UN Convention Against Torture states that governments must prevent any “acts of cruel, inhuman or degrading treatment or punishment” from occurring at the hands of officials.

The Special Rapporteur of the Human Rights Council on torture has previously stated that “the imposition of solitary confinement, of any duration, on juveniles” contravenes UN rules.

But an investigation by The Independent has exposed allegations of solitary confinement being used in young offenders institutions (YOIs), which house 15-18-year-olds, across the UK, despite the Government’s official stance that the practice does not take place.

The Ministry of Justice maintains that “segregation” of minors occurs for their own safety, which can involve them being isolated but not for significant periods of time. However, lawyers claim that “segregation” at some prisons meets the legal definition of solitary confinement.

Under international human rights law, the Mandela Rules define solitary confinement as “the confinement of prisoners for 22 hours or more a day without meaningful human contact”.

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The news comes amid a deepening crisis in the British prison system, which has seen mass walkouts from striking prison staff as well as escalating violence and deteriorating conditions inside jails.

Laura Janes, legal director for the Howard League for Penal Reform, said she had worked with at least six teenage boys under the age of 18 in the last two years who have been in conditions of solitary confinement, for periods ranging from weeks to up to six months. Of these, one boy was placed there for a period of close to four months while another was held for a period of close to three months, she said.‎

Prison inspection reports suggest the Government has known since at least 2015 that “segregation” restrictions amounting to solitary confinement have taken place at some YOIs.

An inspection report written by government prison inspectors following a visit to Feltham YOI in 2015 stated: “Twenty-six per cent of the [prison] population were being managed on units under a restricted regime that excluded them from activities and meant that they were unlocked for less than an hour a day – in effect solitary confinement.”

Inspectors warned: “We found examples of boys … who were locked up for too long with nothing to do and a few cases of boys who said that isolation brought about by restricted regimes had caused them to self-harm.”

They added: “The segregation environment remained grim and quite inappropriate for children, with no suitable facility for face-to-face interventions, such as education.”

In the same year, a report by the National Preventative Mechanism, an independent body which monitors treatment of prisoners, stated of YOIs: “In many cases, isolation outside the formal care and separation unit lasted for more than 22 hours a day, and could last for several weeks … In some instances, children are held for long periods in conditions that amount to solitary confinement.”

The mother of a teenage inmate, who spoke to The Independent on condition of anonymity, said her 16-year-old son, who suffers from a serious mental health condition, was placed in solitary confinement at a number of different institutions over a six-month period last year. She claims while he was there, 13 other boys were also held in isolation units nearby his cell.

She said: “He was on 23 and a half hours in the cell. He was allowed out for a shower or a phone call for half an hour every other day. The cell was disgusting, conditions were filthy. His education was very few and far between; hee was slipped a piece of paper under the door – nothing meaningful for education.”

She said families of prisoners felt unable to complain about the treatment amid fears it would make their children’s lives even harder: “You can’t say anything, it’s a catch-22,” she said. “No one seems to listen, no one seems to care.”

The mother added that now her son has returned to a mainstream prison cell but still struggles with the emotional toll of solitary: “He’s so used to solitary now. He can’t handle human interaction when we visit him with his siblings, he can’t bear to see the children moving about or making noise.”

Another inspection report from 2015 report into Werrington prison in Staffordshire states: “Education outreach visited the unit daily but because of the high occupancy levels boys received as little as half an hour education every other day. We were particularly concerned about the impact on boys’ development of prolonged periods with no activity and limited time in the open air.

“It was inappropriate that the boys were denied access to showers, exercise and telephone calls in response to poor behaviour.”

Lawyer Laura Janes, told The Independent: “Solitary confinement for children isn’t just cruel – it’s also unlawful. Because they’re locked up the whole time, these kids have no sense of time and space. They eat in their cells. There is no education and there is nothing for them to do. They have no meaningful interaction beyond shouting through their cell doors at each other. Their lives become devoid of meaning and full of frustration.

“One boy I worked with was in solitary confinement for most of six months. In prison he was considered too dangerous to mix with others but once he was released, he was fine. It was not about him but the environment he was in. It’s obvious cooping children up will impact on their health; they need exercise and structure.”

Kimmett Edgar, head of research at the Prison Reform Trust, echoed the concerns, telling The Independent: “The UN’s rules on child detention explicitly exclude the use of segregation due to the damaging effects it can have, with research consistently showing that involuntary isolation undermines mental health. The state has a binding duty to ensure the safety and wellbeing of all children and particularly those it detains.”

MrFarron added: “These are some of the most vulnerable members of our society and their time in young offenders institutions must be focused on education and rehabilitation. I urge the Government to investigate these claims.”

A spokesperson for the Ministry of Justice said the Government stands by its position that solitary confinement does not happen in the UK. They said in a statement: “When young people in custody are putting themselves or others at risk, segregation can be used as a last resort for limited periods of time when no other form of intervention is possible.