Inmates at a prison in need of urgent improvement slept with covers over their mouths to stop cockroaches crawling in, ministers have heard.
Bedford Prison was issued with an urgent notification to improve in November, after inspectors found violence, squalid conditions and high rates of self-harm.
The category B reception prison is the fifth to be given an urgent notice in the last 12 months.
An inspection by HM Inspectorate of Prisons (HMIP) found levels of violence against staff were at the highest rate in any adult male prison in the country, while it had the third highest rate of recorded self-harm.
Examples of “unprofessional behaviour” and “excessive force” were seen by inspectors, with the use of force remaining “high”.
The inspection also found new prisoners being placed in dirty cells with limited induction while three quarters of inmates lived in overcrowded conditions with a widespread infestation of rats and cockroaches.
Raising the conditions in the prison, Labour MP for Bedford Mohammad Yasin told the Commons: “I have been told that prisoners sleep with covers over their mouths to stop cockroaches crawling in while they sleep.
“The inhumane segregation unit, once described as a rat-infested dungeon, was supposed to have been shut down years ago, but endless delays to the new unit means it is still in use.
“So will the minister explain what he believes prisons are for?
“Locking people away in these conditions does not keep society safe.
“Where is the rehabilitation in this system?
“Who can leave these conditions a better person, or less likely to reoffend?
“Overcrowded, squalid, and unsafe prisons will never help or allow people to turn their lives around and move on from a life of crime and hurting others.”
Mr Yasin called on ministers to set out their plans to improve the prison, suggesting huge investment and moving inmates to other institutions to tackle overcrowding.
He said: “In 2017, when HMP Liverpool was described as having the worst living conditions ever seen by inspectors, the prison was successfully turned around by significant population reduction, huge investment, and resources were channelled towards the prison.
“Bedford needs this level of sustainable investment now, but in the context of the current capacity crisis, will the minister confirm if such a decanting measure is even possible?”
Justice minister Edward Argar responded: “I am deeply concerned by the recent HMIP findings at HMP Bedford, particularly in regard to safety and living conditions, and I have been clear the situation needs to improve quickly.
“This is, as he set out very clearly, the second time an urgent notification has been invoked at HMP Bedford, and I agree that the circumstances leading to this are not acceptable.”
The minister said his boss, Justice Secretary Alex Chalk, would set out his response to the HMIP inspection by December 15, including an action plan to address the conditions and staffing problems faced by the prison.