A report into a riot-hit jail has revealed inmates were locked up for as much as 23 hours a day and highlighted a failure to provide soap, cleaning materials and toilet paper.
Scores of prisoners flooded the gangways at the Category B HMP Bedford in chaotic scenes in November 2016 and caused extensive damage.
Two wings were "totally trashed with broken furniture, fittings and doors", the Independent Monitoring Board report said.
The report, which covers the period from July 2016 to June 2017, said notes were found stuck to walls on the A wing after the riot saying "this was caused by 23 hour lock-up; peace" and "we need to be treated like human beings".
It notes the number of officers working at the prison in the week before the riot was, at 55, half what it should have been to run a "full regime".
"Whilst the issue of staffing levels was more deeply rooted and difficult to address quickly, the inability to supply, on a consistent basis, basic requirements, such as toilet paper and cleaning materials, was simply shameful," it said.
The report added: "In the days prior to the riot, prisoners were locked up for most of the day and became increasingly angry and frustrated.
"This anger boiled over when prisoners were unlocked for a curtailed period of association on Sunday afternoon.
"Prisoners were apparently wielding improvised weapons and knives, fires were started and some prisoners went on to the netting."
Officers withdrew from the prison and a few prisoners donned helmets and padding from lockers, the report said.
Order was restored after six hours as 126 officers from the National Tactical Response Group quelled the disorder.
The report said there has been "considerable improvement" at the prison in the last few months, but added "until the prison is back to its full complement of inmates, it is impossible to say if these improvements can be sustained".
A Prison Service spokeswoman said: "Transforming prisons into places of safety and reform is our top priority and we are tackling the challenges we face head on."
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