NEARLY one in three prisoners at a Hampshire jail has failed a drugs test in the past 12 months.

Winchester Prison ranks as one of the three worst jails in the UK for substance abuse, according to a report by the Prison Reform Trust.

The damning criticism is contained in a report which also reveals the Isle of Wight's three jails are failing.

Overcrowding at Winchester Prison was also highlighted as an area of major concern, with numbers showing the average population for the Victorian-built jail was 626, while the official accommodation figure is just 437.

It means that 59.5 per cent of inmates are sharing cells designed for just one.

There were also 11 serious assaults during the year - twice the number of the year before, and three suicides - up one from the previous year.

Figures show that the Isle of Wight's Category B Parkhurst prison has the third worst serious assault figures for the whole country, with more than one in three prisoners being a victim.

Parkhurst has an average population of 494 inmates compared to an official maximum of 459, and had some 12 per cent of its inmates test positive for drugs.

Camp Hill, the Island's only Category C prison didn't fare much better.

It headed the serious assault figures for Category C centres across the UK with 18 incidents, amounting to another one in three assault rate for prisoners, though illegal drug use had fallen to below ten per cent.

The only prison to come out shining in the report was Category B prison Albany which managed the lowest drug figures of less than two per cent, the second lowest assault figures of just three, and met its population quota at 506 inmates, seven less than it is certified to hold.

A spokesman for the Prison Reform Trust said: "This report demonstrates that overcrowded jails don't work.

"They are unsafe, inhumane and ineffective. Far too many prisoners are passively serving time when they should be actively paying back the damage they have done to communities.

"If this were aschool report they'd be a huge public outcry, but because most people don't understand or see how prisons work, few seem to care."

Winchester MP Mark Oaten said: "The Prison Service has a duty of care to its prisoners and also a duty to protect society.

"It is very clear that overcrowding places a huge burden on hardworking prison staff and undermines all of their attempts to reform offenders.

"The government simply has to do more to cut prison numbers."

The Prison Service says it has met nine of its 13 performance targets, including preventing escapes, reducing staff sickness and providing better education.

It says it constantly running at full capacity, which is making many aspects of its role more difficult.

A spokesman said that a new drug strategy was in place at Winchester which aimed to combat both usage and supply. She added: "Most drugs are brought in by visitors.

"The prison has now received funding for an extra drug dog, which we hope will detect, and therefore stop, more drugs from reaching the inmates."