The annual cost of keeping each juvenile offender in Oberstown Boys' Centre has reached €250,000 a year.
Oberstown, near Lusk, Co Dublin, was the most expensive of the State's five detention schools in 2003, with a cost per juvenile of €249,283.
This is three times higher than the €87,000 average it cost the Irish Prison Service to imprison an adult offender in one of its prisons during the same period.
The annual cost for the juveniles does not include their education while they are being detained, which is up to €15,000 per child per year.
Details of the costs come at a time when the Department of Education - which is responsible for the detention of young offenders - is considering reducing by almost 25 per cent the number of juvenile detention places at its five centres in Dublin and Tipperary.
Documents obtained by The Irish Times reveal that a committee established to oversee the running of the five centres has told the Government that pressure for beds at the centres will reduce in coming years.
Arising from this, the Special Residential Services Board recommends that 88 beds should be made available at the schools, nearly a 25 per cent reduction on the 114 operational bed capacity at the five centres at present.
The board was provided for under the terms of the Children Act, 2001, and has been operating on a statutory footing since November 2003.
Briefing notes on youth justice prepared for Minister for Education Mary Hanafin show that the board believes the full implementation of the Children Act, 2001, will result in fewer children being sent to detention because of community-based alternatives available once the legislation is fully enacted.
The notes read: "It [ the board] sees both bed capacity and the roles of schools changing in the long term with the increasing availability of early intervention measures and alternatives to custody provided for under the Act.
"This should result in a reduction in demand for residential places for young offenders with a higher turnover and more demanding population."
The board recommended that 88 beds be made available for offenders in the future, along with six step-down beds which would be used as offenders are being prepared for release.
The five Department of Education-run centres currently have an operational bed capacity of 114 beds - 99 for boys and 15 for girls - along with six step-down beds.
The average cost of keeping a child at the five centres in 2003 was €212,430 per annum.
Oberstown Boys' Centre was the most expensive, costing €249,283 per boy per year.
This is followed by Trinity House, Lusk, €246,752; Finglas Child and Adolescent Centre, €245,556; Oberstown Girls' Centre, Lusk, €177,931; St Joseph's School, Clonmel, €142,628.
St Joseph's school is a much larger school than the others and so enjoys economies of scale that do not apply elsewhere, according to the department.
The schools provide residential care, education and rehabilitation for children up to the age of 16 who are referred by the courts.
Children are held for between one and four years.
The five centres employ 530 staff, with around 210 care staff, 40 teachers and 15 directors and deputy directors.
The annual cost of detaining a child for a year does not include teaching costs, which reached almost €2 million last year, or up to €15,000 per child per year.
