15 alleged complaints of assault or use of excessive force were made by inmates at Castlerea prison last year against staff.
The figure was the second highest in the state, with the largest number of alleged complaints of alleged Catgeory A offences recorded at Midlands prison.
Of the six complaints upheld nationally, three were recorded at the Roscommon facility.
Prisoners’ complaints about life behind bars and their treatment are graded by the nature of the complaint lodged from category A through to category F.
Category A complaints are defined in prison rules as complaints alleging assaults or use of excessive force against a prisoner or ill treatment, racial abuse, discrimination, intimidation threats or any conduct against prisoner of a nature and gravity to bring discredit on the Irish Prison Service.
15 of these complaints in the A category last year were made about staff at Castlerea with twelve rejected and three upheld.
In total 76 complaints were made last year at Irish prisons, with just six upheld, and 52 rejected while 10 were deemed as incomplete.
The highest number of complaints received was at the Midlands Prison where 21 issues were brought to the attention of authorities and investigated
New figures from the Minister of Justice show that last year the Irish prison service recorded five incidents where control and restraint techniques were required on prisoners at Castlerea – out of a total recorded by the Irish Prison service of 92 nationally.
The Minister for Justice has also revealed that as of the 6th of July this month, at Castlerea prison, 9 remand prisoners were mixing with sentenced prisoners.