A voluntary testing scheme established to tackle the problems of drugs among prisoners is being hailed as a success.
The programme can help prisoners stay off drugs
Nottingham Prison says that the scheme has helped dozens of inmates to beat their addiction.
The unit can deal with up to 50 inmates with the chance of some prisoners being released early if they remain free from drugs.
Progress at the unit, based at Perry Road, is monitored by officials from the Prison Service.
Like many other jails Nottingham Prison has experienced problems with drugs.
An inmate, known as Alan, had an addiction for nearly ten years, but due to the programme has managed to stay off drugs.
He said: "I used to have a serious problem with heroin.
"I did a clinical detox and then was put on a short duration programme, which helped me look at issues I've got within myself and I've been clean for eight months now."