More than 170 children and teenagers were placed in adult prisons last year, in contravention of international treaties which prohibit the detention of juveniles alongside adults.
The Prison Service has confirmed to The Irish Times that 174 young people aged between 15 and 17 were placed in adult places of detention such as St Patrick's Institution (which accommodates young people aged between 16 and 21), Cloverhill and Limerick prisons during 2005.
This number represents an increase over 2004, when 166 young people were placed in adult prisons. Latest figures for 2006 suggest the numbers are on the rise again, with 163 under-18s in adult jails so far this year.
The number of young people in adult jails is likely to cause embarrassment for the Government at a UN hearing in Geneva next month, when it will be asked to account for its progress in protecting children's rights.
Among the issues the Government will be asked by the UN Committee on the Rights of the Child to address will be the number of under-18s who have been tried as adults; the type of detention centre available for under-18s; and the number of persons under the age of 18 detained in adult facilities.
The placement of children in adult places of detention is in breach of the UN Convention on the Rights of the Child and the European Convention on Human Rights.
However, briefing notes for the Government show it will argue there has been a decline in the number of young offenders under 18 placed in prison custody between 2003 and 2005.
Government officials are also likely to raise plans by the Minister of State for Children, Brian Lenihan, to end the practice of jailing children alongside adults.
The Government has approved reforms that will see the closure of St Patrick's Institution for Young Offenders and the increased use of correctional schools for under-18s. A number of such facilities already exist, such as Trinity House in north Dublin.
Other reforms include raising the age of criminal responsibility for most offences up to the age of 12, which will result in more children being dealt with under the care system rather than the criminal justice system.
While the reforms have been welcomed by the Children's Rights Alliance - a coalition of 80 children's rights groups - it has voiced concern at the Government's timetable, which may not result in the closure of St Patrick's Institutions for at least another four years.
The alliance's deputy chief executive, Maria Corbett, also expressed concern that just two of the 10 community sanctions provided for in the Children's Act have yet been fully implemented.
Ms Corbett spoke of the need for "sustained investment in a range of community-based prevention, early intervention and rehabilitative services".
Geoffrey Shannon, a solicitor who specialises in children's rights and family law, said the detention of young offenders should be a last resort.