In the most recent visit, inspectors found the number of use of force incidents had trebled, violent incidents had increased, and the rate of self-harm was the third highest among the country's category B training prisons.

They said compounding this was the ingress of illicit drugs, with 56% of prisoners surveyed saying it was easy to get hold of them, and 40.6% testing positive in random drug tests in the 10 months before.

The report stated that although a high number of medical emergencies were linked to drugs, health services were no longer providing round-the-clock care, were not meeting the needs of patients, and in some cases were unsafe.

HMIP said the prison's response to recommendations made by the Prison and Probation Ombudsman was also inadequate and not all incidents of self-harm were recorded.

Prisoners said there was inconsistency in the regime and prison systems, difficulty maintaining family ties and an inability to see health professionals were some of the triggers for self-harm.

In December 2023, the government took over the running of the prison from a private provider before making the move permanent last August.

HMIP said since the decision some improvements had been made but they were recent and fragile, and there were many longstanding concerns.

It said 39% of prisoners surveyed said their experience in the jail would reduce their likelihood of re-offending, compared to 57% at the last inspection.

Ultimately, the prison was failing to deliver its purpose as a training prison, it said.

Inspection team leader Hindpal Bhui said: "The prison has had a number of problems over many years, and many of those have become worse by the time of this visit.

"A couple of years ago the contractor changed and this was mismanaged. The new contractor clearly didn't have enough staff to provide a safe prison.

"When we arrived the prison wasn't safe. There was a large amount of drugs getting into the establishment, leading to tragic cases of deaths in custody.

"We gave Lowdham Grange the worst possible scores on safety, respect and decency.

Mr Bhui added: "It is a prison with high violence, lots of drugs getting in, lots of self-harm, and a healthcare service which is overwhelmed and unable to deal with the consequences of all those factors and that leads to fundamentally a dangerous prison."

HM chief inspector of prisons, Charlie Taylor, added: "Although there were many challenges at Lowdham Grange, the new governor had established an understanding of the key issues that needed to be addressed, and inspectors left with some hope that the chaos seen at recent visits had started to subside."