The prison watchdog has warned the safety of inmates at one of the country's most notorious jails cannot be guaranteed.

A hard-hitting report by chief inspector of prisons Anne Owers also concluded that Parkhurst prison on the Isle of White is perceived as "institutionally racist" by Black and Asian prisoners.

She described her findings into the jail - which has housed notorious criminals such as the Kray twins - as "extremely depressing".

Owers warned conditions for the 500 prisoners have deteriorated in the two years since the prison was last inspected.

"It does not appear that Parkhurst has properly readjusted to its role as a training, rather than a high security dispersal, prison," she said."It needs swift, co-ordinated and sustained action by local and regional managers to recover from its present position and to bed in the attitudes, practices and opportunities that can ensure a positive and safe environment."

The latest critical report by the watchdog in three weeks highlights the growing crisis in Britain's jails caused by overcrowding in buildings that in some cases are centuries old.

Key problems included new prisoners, including young men on remand, being placed with violent and disturbed criminals in the segregation unit.

Prisoners from ethnic minorities told inspectors they felt "powerless" and the report reveals why.

"This was unsurprising - there was no race relations liaison officer, a race relations management team which had not met for 11 months before the inspection and no information about racial incidents investigated over the last six months."

"These issues need to be addressed as a matter of urgency," the report concluded.Head of the Prison Service Phil Wheatley accepted that conditions had been poor but claimed problems had been largely addressed by the new governor and his management team.

"The inspection team visited at a time of severe staff shortages when a series of disturbances by prisoners and a rise in the population helped to create a climate where dealing with immediate crises had briefly to take precedence over the more constructive work of the prison," he said."The inspector's concerns about the inappropriate housing of prisoners in the segregation unit have been dealt with by the establishment of a new first night centre and the removal of vulnerable prisoners to a different wing. I am confident that HMP Parkhurst is becoming a decent, safe prison and will continue to improve."