UP to 40 inmates are granted temporary release from prisons around the country every day -- but authorities have no idea how many reoffend while on the outside.
Figures released to the Irish Independent show that over the last two years, an average of one out of every six prisoners was on temporary release at any given time.
In most cases, the inmates are being let out to help alleviate overcrowding.
However, the Department of Justice has said that due to financial constraints it is unable to monitor or record how these inmates behave when they're out of jail.
"The gathering of such information would require a disproportionate and inordinate amount of staff, time and effort," a department spokesperson said.
"It could not be justified in current circumstances where there are other significant demands on resources."
In recent years there have been some notable instances of prisoners getting involved in serious crime while out under the temporary release scheme.
In December 2009, 26-year-old Brian Casey of Lissycasey, Co Clare, died as a result of an assault by Harry Dinan and his nephew Kevin Dinan.
The attack on the young teacher was described in court as "cowardly and unprovoked".
Harry Dinan was on temporary release when the attack took place, despite having 64 previous convictions.
He was later jailed for five years for the assault.
Figures show that at the beginning of January last year, 30pc of the inmates in Cork Prison were on temporary release.
Some 137 prisoners were out of jail, mainly due to significant overcrowding. High numbers -- 28pc -- were also on temporary release from the Dochas Centre.
A month earlier, the prisons granting temporary release included the Dochas Centre (38pc); Cork Prison (33pc); Mountjoy (23pc); Wheatfield Prison (14pc); and the Midlands Prison (11pc).
When compared with December 2010, the figures -- released under the Freedom of Information Act -- show a stark increase across the board in the number of prisoners granted this special privilege.
A year earlier the temporary release figures for the Dochas Centre stood at (27pc); Cork Prison (30pc); Mountjoy (16pc); Wheatfield Prison (10pc); and the Midlands Prison (5pc).
Increasing pressure on prison space nationally has also lead to a rise in the practice of "doubling-up".
This sees certain prisoners forced to share cells, placing both inmates and staff at increased safety risk.
This comes as overcrowding is set to reach unprecedented levels with the long-fingering of two new prisons planned for Thornton Hall, Co Dublin and Kilworth, Co Cork.
It was originally proposed that Thornton Hall would cater for 2,200 prisoners with a further 450 designated at Kilworth.
However, the Thornton Hall review group subsequently recommended a reduced capacity of 500 and 300 respectively.
The department has now shelved the building of both prisons for the immediate future due to budgetary constraints.