The latest report from the chief inspector of prisons has blamed overcrowding for poor standards at Pentonville jail.

During an unannounced visit last September, inspectors found that inmates spent little time out of their cells, and educational facilities had been closed due to staff shortages.

Access to showers and changes of underwear was limited to roughly once a week, while risk assessments were not performed on prisoners required to share cells, and "considerable improvement" was needed on work to reduce incidents of self-harm.

A total of 57 recommendations were made in Anne Owers' report.

"We fully recognise the difficulties that the prison was facing at the time of the inspection," she said.

"To a great extent, they reflect endemic problems in the prison system, particularly in the south, as a consequence of the rising number of prisoners and the difficulties in staff recruitment.

"The prison hoped and expected that the arrival of additional staff would make a significant difference to the regime. However, we suspected that there were underlying issues of staff deployment, in combination with prison overpopulation, that will make it difficult to remedy the substantial deficits we found."

Prison reform charities condemned the findings set out in the report.

"The chief inspector's devastating report on Pentonville must act as a wake up call to government to avoid legislative measures which are bound to inflate the prison population still further," said Juliet Lyon, director of the Prison Reform Trust.

"Currently, large local jails are simply operating as vast transit camps for offenders. With 40,000 prisoners in and out of Pentonville last year we can forget about preventing reoffending. Containment is all it can be expected to manage."

Although Pentonville prison was praised for its healthcare, drug schemes and offending behaviour programmes, it was noted that, at 25 per cent, the proportion of ethnic minority inmates was considerably higher than in other institutions.

"We suggest that, with the new staff in place, the governor and area manager together should review the regime and activities and realistically assess what the prison can provide," said Owers.

"If that analysis identifies that there cannot be a decent regime unless there are fewer prisoners, or more staff, that message needs to be sent clearly to the Prison Service, ministers and the public."

The jail was defended by the director general of the Prison Service, Phil Wheatley.

"Pentonville's regime over the past six months has consistently met its targets and has exceeded its targets on purposeful activity and education," he said.

"The prison has completed the highest number of offending behaviour accreditations of any prison and prisoners now have daily access to showers.

"It was unfortunate that four days before the inspection team arrived, the prison had to deal with a series of serious acts of indiscipline which had required the temporary shutdown of the normal regime whilst the situation was stabilised.

"Ironically, the month after the inspection team left Pentonville, 15 officers from the London-wide recruitment campaign started work at the prison, which has now been fully staffed since January 2003. In my view, Pentonville today is a safe and decent prison coping professionally and compassionately with the huge numbers of prisoners passing through the gates every day."