A watchdog has called for Winchester prison to be put into emergency measures amid concerns over “very high levels of violence” and drug problems.

Prison inspectors wrote to Justice Secretary Shabana Mahmood to issue an urgent notification for improvement at the category B jail in Hampshire after “very poor” inspection findings.

Drug use was “rife”, but the prison’s approach to testing was “weak”, and a third of CCTV cameras were broken which “compromised security”, the watchdog warned.

These very poor outcomes represent systemic failings

Some 41% of the around 690 men held there tested positive for drug use in August, and 47% reported it was easy to get hold of illicit substances, inspectors said.

The prison, which also has a lower security category C resettlement unit, was so “dilapidated” one inmate had “been able to remove his own cell door”, the watchdog’s inspection carried out earlier this month found.

Drugs, debt and “prisoner frustration” led to the “highest level of serious assaults” against staff in all England and Wales reception jails – which process new inmates into the prison system and hold people on remand or who have been convicted but yet to be sentenced while they are taken to court.

It also had the second highest rate for serious assaults against other inmates, while self-harm was at the third highest level of all prisons of this kind, according to the watchdog.

Martin Lomas, deputy chief inspector of prisons, said: “Winchester was in a very poor state and had been for many years.

“At this most recent inspection we found that standards had deteriorated to the point that we had no choice but to issue an urgent notification for improvement.

“These very poor outcomes represent systemic failings under the oversight of HMPPS (HM Prison and Probation Service) and the Ministry of Justice, and will require sustained support and investment if the jail is to provide decent living conditions, keep prisoners safe and provide them with the skills they need to succeed in life outside prison.”

Inspectors also highlighted how prisoners were being held in “dreadful conditions” with some cells “so damp and mouldy that inspectors questioned whether they were fit for habitation.”

Winchester is the ninth prison to be issued with an urgent notification since November 2022, joining Exeter, Woodhill, Bristol, Bedford, Wandsworth, Rochester and Manchester jails as well as Cookham Wood young offender institution. This is the second warning of its kind the watchdog has made this month.

The notice effectively places the jail in special measures and means the Justice Secretary has to urgently produce an action plan for improvement before the watchdog carries out another inspection.

Prisons minister Lord Timpson said: “This report illustrates the scale of the crisis this Government inherited in our prisons.

“Prisons like HMP Winchester must not be allowed to become breeding grounds for further crime. Staff are already working hard to drive the improvements needed and we will publish an action plan in the coming weeks to support them in their efforts.”

The full findings of the latest inspection which prompted the urgent notification will be published at a later date.