NHS hospital admissions for drink and drug abusers rose by almost a third in three years, according to a report.

The study also found that between 1996 and 2006 the number of beds on NHS mental health wards fell, but the number of patients rose 20 per cent.

By 2006, sectioned patients were only five times more likely to be in an NHS facility than a private one, compared with 15 times more likely in 1996.

The increase in drink and drug admissions up to 2006 changed the environment on inpatient psychiatric wards, according to the report's authors, led by consultant psychiatrist Patrick Keown.

Professor Scott Weich from the University of Warwick wrote in an accompanying article in the British Medical Journal: "These numbers say nothing about the quality of service or the experiences of users, carers, and staff."

"The recent national review of inpatient services by the Healthcare Commission, in which 59 per cent of trusts were rated as fair or weak, does little to allay concerns about lack of care and planning and impoverished physical environments."

He added: "Where things are bad, they are very bad, and these are the places where the needs of the most excluded, vulnerable, and disaffected (including those from black and minority communities) are least adequately met."

The report's statistics were branded "ironic" by mental health charity SANE.

Chief executive Marjorie Wallace said: "It is ironic that, having drastically reduced the number of psychiatric beds in the NHS, the Government now has to rely on the private sector to accommodate the dramatic increase in the number of people detained involuntarily.

"Improvements in community care are supposed to reduce the need for compulsory admission when someone reaches crisis point - yet precisely the opposite appears to have happened. We urgently need to find out why this is the case.

"We are also worried about the truly shocking state of many wards on which the most disturbed people are being detained. If someone's freedom has to be taken away, society has an extra duty of care to ensure they are kept in safe conditions and given therapy, not punishment, for an illness for which they are not to blame."

Liberal Democrat Shadow Health Secretary, Norman Lamb said: "The hidden costs of drug and alcohol abuse are affecting every area of the NHS.

"Under-funded and under pressure mental health services are ill-equipped to deal with this extra pressure.

"The Government must focus on tackling drug and alcohol abuse before it forces people into the already overstretched mental health system."