Inmates at Bristol prison were admitted to hospital seven times over six-months after taking banned legal high Spice, it has been revealed.
A report by HM Inspectorate of Prisons found that a mandatory drug testing regime did not detect Spice, a synthetic drug used to imitate the effects of cannabis.
It is believed to have become one of the main drugs of choice inside the jail.
The Inspectorate praised Bristol Prison for making considerable progress but says significant concerns still remain.
They found the most serious issue identified at the prison was the level of violence, which was much higher than in similar prisons.
A report by the HM Inspectorate of Prisons has expressed concern over the quality of accommodation at Portland Prison. There have been three deaths there since the last report. But inspectors have praised the insitiution for its lack of violence amongst offenders.
It's been confirmed that Dorchester Prison is to close and discussions are underway to end the lease at Dartmoor Prison.
Elsewhere, Portland's Verne Prison will be turned into an immigration detention centre.
The former Victorian military barracks, transformed into a jail more than 60 years ago, will become a Home Office immigration unit housing people waiting to be removed from the UK.
Duncan Sleightholme reports:
The Conservative MP for South Dorset Richard Drax said he was pleased the building would remain open with the prospect of more employment:
The Justice Secretary Chris Grayling said the prison will be turned into an immigration removal centre:
The Justice Secretary Chris Grayling said he regretted the decision to close the prison:
The Ministry of Justice said work to close HMP Dorchester will begin immediately and it is expected to shut close at the end of the year.
Everything will be done to avoid compulsory redundancies and our intention is for all staff to be redeployed to alternative roles in the prison estate or, if necessary, offered the opportunity to leave on voluntary terms.
Offenders housed at Dorchester will be moved to other suitable prison accommodation.
Existing staff will continue to run the site but the Home Office will meet the costs of its operation. Offenders housed at The Verne will be moved to other suitable prison accommodation.