The next highest in terms of cost is the North, at €900 per day, followed by the Netherlands, at €608.
Although there is no figure for 29 of the 53 jurisdictions covered, the Council of Europe said the cost in Ireland was “by far the highest” across Europe.
Estimating the amount spent per day for the detention of one person in an institution for juvenile offenders in 2014, the cost in Ireland was €2,773, compared to the EU average of €284.
The data, contained in the Council of Europe annual penal statistics, includes countries in eastern Europe, the Balkans, the Caucasus, as well as Russia, where the costs are far lower.
Ireland’s institutions for the detention of children are based at Oberstown in north Dublin.
Ireland is also above average in terms of the average cost for the detention per person in all penal institutions, including the country’s prisons for adults.
The cost stands at €189 per day per inmate, compared to the European average of €101. In England and Wales it costs €116 and in Scotland it is €125 per inmate.
Figures show Ireland is significantly lower than the European average in the ratio of its people that are imprisoned at 80 per 100,000 inhabitants compared to an average of 135 per 100,000.
Ireland’s rate is significantly below England and Wales (148), Scotland (145), and Northern Ireland (91.5) In Russia, it stands at 440.
The average age of prisoners is 34 in Ireland, compared to the overall average of 36. Of the EU countries, only France had a marginally lower average (33.8).
Although numbers of female prisoners have been increasing in Ireland in recent years, females account for 3.4% of the population compared to the total average of 5.4%.
In terms of types of crimes, Ireland scores higher for certain offences: assault (15% of the total, compared to the average of 9%); rape (5% v 4%); and other sexual offences (6% v 4%).
Those serving life sentences in Ireland account for 11% of all sentenced inmates — compared to 3.5% generally. But the figure is similar to our neighbours: England and Wales (10%); Northern Ireland (14%); with Scotland the highest (17%).
The average length of imprisonment in Ireland is 2.8 months, compared to the total average of 11 months. Ireland’s average is lower than England and Wales (8.5 months) and Northern Ireland (5.5 months).