Plans to treat more mentally ill offenders and drug users in the community rather than sending them to jail are admirable but "fraught with difficulties", the probation union Napo warned today.
Harry Fletcher, assistant general secretary of Napo, said the Government would need to find hundreds of millions of pounds to make the proposals a reality.
His comments came as the Ministry of Justice published its business plan for the next four years.
"The aim of transferring mentally ill people and drug users from prison into health care is an admiral one, however it is fraught with difficulties," Mr Fletcher said.
"Currently there are 1,500 secure beds and an additional 40 or so medium secure regional units for mentally ill people. All are running at capacity.
"The Government therefore will need to find hundreds of millions of pounds to build new facilities."
He went on: "It is difficult to see how the prison population can be reduced.
"Indeed cuts to probation and social security benefits suggest that the prison population will actually rise within the next three years."
The proposals were part of the ministry's plans to cut the 85,000 prison population in England and Wales by 3,000 over the next four years.
Introducing the plan, Justice Secretary Kenneth Clarke said: "Our programme of fundamental reform will result in a revolution in rehabilitation that will reduce reoffending.
"We will ensure that those who break the law are punished.
"But by helping offenders get off drugs, move into work, and manage mental illness we will see fewer of them slipping back into lives of crime.
"Prisons will be places where meaningful work and opportunities to reform are the expectation for prisoners, not a matter of choice."
He went on: "Despite the ambition and determination of those working within the justice system, there is too much litigation, too many people reoffending and too much money spent on systems.
"By 2015, the department will provide services in a completely different way."
Graham Beech, strategic development director for crime reduction charity Nacro, added: "What is proposed represents a radical change which will open up opportunities for charities like Nacro to play an even greater role in reducing reoffending and making society safer."Reuse content