Inmates at a “substandard” prison claimed it was easier to get hold of drugs than clothes or bedding, a watchdog has found.
The report on HMP Bedford found almost twice the number of prisoners said it was “easy” to access drugs, compared to a previous inspection in February 2014.
It also discovered incidents of self-harm had almost doubled from 67 to 121.
The Prison Service said it was taking action to address the level of substance misuse at HMP Bedford.
The critical report sets out the findings made by the HM Inspectorate of Prisons in May.
It found that of 72 recommendations made after the prison was last inspected more than two years earlier, only 12 had been achieved and four partially achieved.
The report found the use of drugs previously known as “legal highs” was having a “serious impact” on safety at the prison.
The use of the psychoactive substance Spice – which mimics cannabis – was prevalent, inspectors found.
Details of damaged furniture, graffiti, shortages of clothing and dirty, unscreened showers were also noted.
Peter Clarke, chief inspector of prisons, wrote: “The stark reality is that prisoners told us it was easier to get illegal drugs in the prison than it was to get clothes or sheets.
“Standards in the prison have declined to unacceptable levels.
“I am not suggesting that staff at HMP Bedford are not working hard – they clearly were, and some important things had been put in place to improve things in the future.”
The prison held just under 500 male prisoners at the time of the inspection.
Frances Crook, chief executive of the Howard League for Penal Reform, said Bedford was “a good example of everything that is wrong with the prison system”.
She added: “It is unsafe, overcrowded and understaffed. Prisoners can obtain drugs easily but cannot get essentials such as clothes and sheets.”
A Prison Service spokeswoman responded: “Safety in prisons is fundamental to the proper functioning of our justice system and a vital part of our reform plans.
“There are a number of factors, including the availability of psychoactive substances, that must be tackled. We are rolling out mandatory nationwide testing of synthetic drugs, which will help to end the flow of these dangerous drugs into our prisons.”