The Inspector of Prisons has strongly criticised prison management and prison officers in relation to the death of 24 inmates.
The report by Judge Michael Reilly found that a management structure did not exist or was deficient in relation to the checking of prisoners while in their cells
Judge Reilly found prisoners on Special Observation were not checked in accordance with standard operational procedures, that risk assessments were not carried out before prisoners were given temporary release, and inmates records, including medical records, were incomplete.
He also found cases where Governors’ and Chiefs’ orders were not complied with and CCTV coverage was not adequate.
Minister for Justice Frances Fitzgerald said she has been advised that the Prison Service was acting on the inspector's recommendations and all necessary steps were being taken to address the deficiencies.
A separate report by Judge Reilly described the Separation Unit at Mountjoy Prison, which is used to detain prisoners on protection, as unfit for purpose, dirty and overcrowded and says it should be closed.
Judge Reilly described recreation facilities at the unit as non-existent and said there were virtually no education facilities there.
He said he found toilets that would not flush, broken windows and razor blades discarded in toilets which posed a danger to both staff and inmates.
He said the unit, which was set up to separate prisoners under threat, was filled with tension.
The inspector also strongly criticised the continued detention of 17-year-olds at St Patrick's Institution in Mountjoy.
He described the treatment of children there as "inhumane and tantamount to holding inmates in isolation".
Ms Fitzgerald promised, as Minister for Children last year, that St Patrick's Institution would be closed.
"One of the Government's priorities is to remove 17-year-old offenders from the adult prison system," she said.
"The detention of children in St Patrick's Institution will end with the provision of more appropriate accommodation and regimes in the new detention facility at Oberstown later this year.
"My department is also taking steps to prepare the general scheme of a bill to provide for the complete closing of St Patrick's Institution."
She added: "Finally, I note the Inspector's concerns that the Training Unit is not being utilised to its potential and look forward to receiving his report on the Training Unit in the coming year.
"I am sure more can be done and I am confident that the Prison Service will do what is necessary."
She also said that tension levels in the Separation Unit since the inspector's visit have significantly abated and that a phased closure plan is currently being developed by the Irish Prison Service.