The number of assaults on staff in the state's detention centre for young offenders nearly doubled last year.
Children attacked staff 40 times in Oberstown in Dublin in 2021, compared to 21 the previous year.
The latest figures show there are 28 boys and no girls in the Lusk centre. Three of them have been detained at the facility for at least four years.
Former Mountjoy prison governor, John Lonergan, says the number of assaults is quite low;
"Confined against their will, often with many many long records of violence and antisocial behaviour and many difficulties in terms of their own behaviour; personality disorders, some of them may be with certain mental health issues. So on balance I would have expected a lot more."