Concerns have been raised over staffing levels and violence at a Norfolk jail.
Almost half of staff at Wayland Prison, near Watton, are in their first year of service according to its independent monitoring board.
And in its annual report, the board says 20 of 72 new officers who were recruited during 2017/18 left in less than a year.
'This has an impact on the safety and discipline on the wings, with less time for communication with offenders known to the officers,' the board's report says.
'The new officer management model due to be implemented last year, where each officer will have a caseload of six to nine offenders, and hold 45 minute sessions with each one each week, is not working due to lack of staff yet to be trained and many redeployed to different wings amongst other difficulties.'
The board says it is concerned at the number of violent incidents which have occurred at the Category C prison, which houses 1,000 inmates.
'In the reporting year the number of reported serious incidents included 214 assaults offender on offender, and 84 assaults offender on staff,' it says.
The board says trafficking and detection of mobile phones and drugs into prison remains a problem, putting a burden on healthcare and leading to debt and threats of violence.
Its chairman Trish Phillips said: 'As a board which monitors fairness and respect for those in custody, the members are alarmed by the large amount of drugs that get into HMP Wayland.
'This has a profoundly bad effect on the prisoners, not only the physical effect of the drugs, but because it results in debt.'
The report says a 'totally unacceptable' number of offenders have not been assessed, with the number increasing from 154 to 206 inmates.
It adds: 'It has great implications for sentence planning and for offenders to progress towards release.'
The board says allowing prisoners to have phones in their cells was a positive move.
'Maintaining contact with family and friends is thought to be one of the main contributors to reducing re-offending on release,' its report says. 'Not having to queue to make a telephone call in an area with no privacy, enables prisoners and families to maintain contact more easily, at times to suit working families and children.'
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