The new Chief Inspector of Prisons has condemned Dartmoor jail after finding that some prisoners had been held in cages more appropriate for dangerous animals.

Anne Owers, the Chief Inspector, today says that prisoners were routinely abused and degraded by officers at the Devon jail, which she describes "as the prison that time forgot". She found that inmates were exercised in tiny pens and forced to use a "walk of shame" route as they were taken to the segregation unit.

Her hard-hitting report is a serious embarrassment for the Prison Service which holds its annual conference on the theme of "Delivering Decency" next week.

Martin Narey, the Director General of the Service, has already told staff at Dartmoor that the prison's role is not that of a punishment block. He will bluntly tell prison staff at the conference that the kind of culture and attitudes found at Dartmoor will not be tolerated in future.

Ms Owers details a catalogue of complaints about conditions at the prison which has a "hard" reputation and for 200 years has been viewed as the end of the line for the most difficult offenders.

The Chief Inspector and her team were horrified to discover that some prisoners in the segregation unit had been held in an "appalling" wire mesh cage despite an order from the governor that the practice be ended.

Inspectors said that they discovered the cage with disbelief and described the practice as ritual humiliation.

Prison officers described inmates as "rubbish" from the rest of the jail system and a manager referred to prisoners in the segregation unit as "crap" and "shit", the report says. Prisoners were also described as vermin and as a prisoner arrived at the unit, an officer had shouted: "Another f inadequate for you."

In her report Ms Owers says: "We discovered a prison which was itself imprisoned in its own past - locked into unsuitable but historic buildings and, more importantly, into an outdated culture of over-control and disrespect for prisoners."

Her report again raises the question about why senior managers in the service are either not alerted or unable to take speedy action to deal with serious problems. Sir David Ramsbotham, the previous Chief Inspector of Prisons, frequently complained that it was only after he arrived at jails that action was taken to deal with problems.

Jerry Petherick, the area manager in the South West which includes Dartmoor, had been in the post since May 2000. A year later Martin Narey, the Director General of the Prison Service, visited the prison and was appalled at what he found.

The governor, John Lawrence, moved from the jail two months after Mr Narey's visit and an acting governor has been in charge since then. Mr Lawrence, previously deputy at the jail, is now seeking retirement on medical grounds.

The report, which was welcomed by Mr Narey as hard-hitting but perceptive, also raises the question, frequently asked as to whether governors' authority is obstructed by the Prison Officers Association (POA).

The report reserves its strongest criticism for the segregation unit, which is now not used. Prisoners are put in segregation units for their own protection, as a punishment or to ensure good order in the jail.

Inspectors say that the prisoners had been exercised one at a time in what staff referred to as pens: 12ft square granite-walled enclosures with rusty gates. The cages - a wire enclosure with a Perspex square through which inmates could communicate their problems - were used for suicidal inmates or others needing a private interview.

"The pens and cages were degrading, and more appropriate for dangerous animals than for potentially suicidal medium to low-risk prisoners," the report says. The cage was dismantled during the inspection in September in spite of a governors order weeks earlier that it be.

There was frequent use of control, restraint and special cells in the segregation unit.

Inspectors said that they witnessed what may have been overuse of force by officers moving a mentally ill prisoner to the block. Seven warders wearing protective gear were involved in the incident which had left other inmates clearly shaken and frightened.

Dartmoor has been reclassified from a Category B to a Category C jail dealing with low risk offenders.

Beverly Hughes, the Prisons Minister, had no comment to make on the report.

Trevor Horn, chairman of the Prison Officers Association branch at Dartmoor denies allegations that staff had bullied or assaulted inmates.

He said that he failed to see why the report criticised staff so harshly. "We do not bully and we are not violent towards inmates," he said.

"If they (the Prison Service) send us their problem children they are dealt with fairly and equally. We cannot recognise what they are talking about in this report".

Mr Petherick said: "Some members of staff have been advised about their behaviour and have been given retraining in certain aspects."

Richard Garside, of the crime reduction charity Nacro, said: "Offenders are sent to prison as punishment, not for punishment. The conditions that the Chief Inspector found at Dartmoor prison are completely unacceptable on humanitarian grounds.

"Prisoners respond best when they are treated with dignity, humanity and respect."