A prisoner has claimed his three-month stay behind bars was like being in a "concentration camp" and alleged rats ran through his cell.
Luke Hudson, from Barnsley, was released last month after being held in both HMP Hull and HMP Humber for assaulting a police officer.
But since his release, Luke has claimed that there were rats "seven or eight inches long" running around his cell in Hull.
He said: "When I saw the rats running around during the day climbing up the windows, I thought ‘wow that’s bad’.
"But then it happened at night. I heard rustling in the rubbish bag.
"I was on the top bunk, but I was just thinking they can climb. I didn’t want an incontinent rat or a mouse weeing and pooing all over me while I'm asleep.
"Surely this shouldn’t be happening in the 21st century? The only way I can explain HMP Hull is it’s like a concentration camp."
The 32-year-old claimed he raised the issue with prison staff, but alleged his complaints were brushed aside.
He said: "All I got out of them was: ‘What do you want? A five-star hotel?’."
A spokesperson for the Prison Service said inspections found no evidence of rats.
It also found there was "no wrongdoing" after a thorough investigation into staff behaviour.
Midway through his time Luke was transferred 18 miles west to HMP Humber, near Everthorpe.
Here, he claims he was threatened by a member of staff who stormed into his cell. The Prison Service denies this.
"They [the officer] said: ' I can make your life hell while you’re in here'," he alleged.
"For an officer to speak to me in such a derogatory manner without any provocation was totally disgusting from a professional.
"They do it quite frequently. I have seen them bullying some of the other prisoners. They do it on purpose to wind people up and get a reaction.
"I have worked in trusted roles myself. I've worked for the NHS. I wouldn't dream of speaking to anybody like that, so why should anybody speak to me like that? It's an abuse of power.
"I can honestly say every other staff member I came across and worked with was absolutely fantastic, but obviously this prison officer is in the wrong job."
A Prison Service spokesperson said: "All complaints by prisoners are taken seriously. These alleged incidents were investigated thoroughly and no wrongdoing was found."
They also told YorkshireLive that Luke declined the offer to hear the outcome of the HMP Humber investigation after his release.
The spokesperson added that a pest control contractor visits HMP Hull every fortnight to carry out "preventative measures" and there has been no evidence of rodents in the Category B prison.
