The State has paid out almost €9m in compensation and legal fees to staff and prisoners due to assaults and "slopping out" practices - including €100,000 to two families whose relatives died from "self-inflicted" wounds.
The figures have been given to TDs amid ongoing concerns over overcrowding and safety levels in jails.
In a detailed letter to the Public Accounts Committee, the Department of Justice's secretary general Aidan O'Driscoll said between 2014 and last year the Irish Prison Service and State Claims Agency paid out €8.3m to victims of assaults or injuries.
The figure includes €2.4m in compensation payments and €5.9m in associated legal fees - €2.7m of which relates to "slopping out" cases.
A breakdown of the figures show:
In addition to the pay-outs, Mr O'Driscoll also confirmed officials paid the families of two prisoners €50,000 and €51,737 in 2016 and 2017 respectively.
In his letter, he said: "The payments were made to the families of prisoners who had died from self-inflicted injuries while in custody."
The scale of the payments and legal fees - and the €100,000 in payments to the families of two dead prisoners - is likely to cause significant concern among human rights groups due to repeated fears over the scale of overcrowding in some Irish prisons.
However, Mr O'Driscoll sought to downplay the concerns by saying there are no international comparisons available to show if Ireland's pay-outs rate is within norms, other than the fact our 5% rate of the population being in prison is not unexpected.
Speaking at last week's PAC meeting, committee chair and Fianna Fáil TD Sean Fleming said there is a clear need to obtain further information on the scale of injuries in prisons.
He added that it is "very sad to be reading that €50,000 and €51,000 has been paid respectively in payments to the families of prisoners who died from self-inflicted injuries in custody". He said the department must clarify exactly what the cases involved.
The fresh questions to the Department of Justice came after the Irish Examiner reported last month that a number of prison officer sexual harassment protected disclosure complaints have been made by jail staff since last summer.
The department confirmed five sexual harassment protected disclosure complaints have been made since last July by staff concerned over their personal safety in work.