The Government decision to move the Central Mental Hospital to a site in north Dublin which will also accommodate Mountjoy Prison when it moves has been condemned as "disastrous" by Schizophrenia Ireland.
The plan to locate the two services adjacent to each other had been signalled as far back as 2004 but was only finally approved by the Cabinet earlier this week.
John Saunders, director of Schizophrenia Ireland, claimed the real drivers behind the decision were cost and convenience, not client needs.
"Locating a prison and a psychiatric hospital together at Thornton will stigmatise people with mental illness even further, and criminalise those with mental illness who are being jailed when in fact they need help and care," he said.
The move however was defended by the Minister of State with responsibility for mental health, Tim O'Malley. He said no matter where a mental health facility was put, people would object to it.
There had to be high security at the hospital and the best advice he got was to locate it adjacent to the new prison, he said.
Over 95 per cent of its admissions are from within the prison service, he added.
Minister for Health Mary Harney said yesterday the Department of Finance would fund the building of the new hospital and, once patients moved to it from Dundrum, the old site would be sold by the Office of Public Works (OPW).
The money raised from the sale of the Dundrum land, which she said "will certainly go out of State ownership", will be "kept in the health services and my preference is in the mental health area".