Inpatient psychiatric services risk providing 'little more than custodial care' because of 'an acute shortage of nurses and a heavy reliance on temporary staff', the Mental Health Act Commission has warned.

Its biennial report highlights mounting pressure on beds and a lack of skilled staff to deal with an increasingly disturbed inpatient population.

'Where there is an impoverishment of the ward skill-mix, therapeutic regimes are likely to suffer, resulting in the provision of little more than custodial care,' the report says.

The policy shift towards community care has created an inpatient community with 'more acute symptoms and high levels of disturbance'.

'Problem behaviour', including drug and alcohol abuse and racial and sexual harassment, has become 'a growing concern'.

Bed occupancy rates averaging 99 per cent are blamed for delays in urgent admissions and early and inappropriate discharge of patients.

Particular problems are identified at high-security hospitals, with 'a national shortage' of medium and long-term secure beds leaving hundreds of patients 'entrapped' as they await transfer.

The report estimates that Ashworth special hospital is home to 200 patients who do not require high levels of security, while 112 patients detained in Broadmoor were identified as 'progressing towards transfer or discharge'.

At Rampton, four patients granted conditional discharges by mental health review tribunals were still at the hospital more than six months later.

The report flags up the government's commitment to providing additional medium-secure beds as a measure which should 'go some way towards alleviating' pressures on the three institutions.

The commission's eighth report is the first to examine the circumstances surrounding the deaths of detained patients. In the year from February 1997, 81 deaths from unnatural causes were recorded.

The commission found 33 cases in which there were 'issues of concern regarding risk assessment, observation levels, leave/absence without leave arrangements and ward security'.

The report pledges to make public findings of a further study when last year's figures are available.

Mental health charities welcomed the report, which was described by Sane as 'the most devastating indictment yet of a system at flashpoint'.

Mind said 'inadequate numbers of qualified nurses' had created a culture of 'control without care' on a significant number of wards.

Chief executive Judi Clements said the report showed the importance of the much-delayed mental health national service framework.

The Mental Health Act Commission Eighth Biennial Report 1997-1999.

Stationery Office.£14.