Persistent criminals aged 12 to 15 will cost an estimated pounds 200,000 to pounds 250,000 a year to keep at the forthcoming secure training centres.
The expense of the privately run units was attacked yesterday by probation officers who argued that the money could be spent more effectively. They will cost six times more than a boot camp, about 50 per cent more than local authority secure accommodation, and twice as much as a room at the Ritz.
Group 4 plans to open a secure training centre at Cookham Wood, Kent, in April which will house 40 persistent offenders aged 12 to 15.
Jack Straw, the Home Secretary, caused outrage among penal reformers when he announced in July that he was to go ahead with a modified version of his Tory predecessors' plans for five mini "jails" despite arguing against them in Opposition.
Figures obtained by the National Association of Probation Officers suggest that the cost per offender per year at Cookham Wood will be at least pounds 250,000 - pounds 5,000 a week. Group 4 refused to comment on costs, but sources suggested that the figure was less - around the pounds 200,000 mark.
Either amount compares unfavourably with current accommodation. A place in a local authority secure unit costs about pounds 130,000 per year and pounds 32,000 in the Government's military boot camp; at Long Lartin high security prison the cost is about pounds 50,000, while a deluxe bedroom at the Ritz hotel in London costs pounds 355 a night or the equivalent of pounds 130,000 a year.
The high cost of Cookham Wood is partly due to the intensive training and education provided and the high number of staff - there will be about 100 for 40 residents. The offenders will each have their own secure bedroom and the centre will have a fence around it.
The Government has given the go-ahead to build five new secure training centres for 200 youngsters who have committed three or more offences. A new detention and training order for young offenders is contained the Crime and Disorder Bill.
Harry Fletcher, assistant general secretary of the National Association of Probation Officers, said: "The resources would be better used either by a consortia of local authorities or managed by the Department of Health."
The four other centres, which have yet to obtain planning permission, are intended for Campsfield near Oxford, Gringley in Nottinghamshire, Onley, Warwickshire, and Medomsley, Co Durham.