A member of a new prison reform group set up in Northern Ireland has said the Prison Service has gone beyond the point of crisis.
Queen's University professor Phil Scraton of Action Prison said the treatment of inmates with mental health issues is simply not good enough.
It follows the deaths of three people in prisons within the past month.
Professor Scraton says the prison service was not fit for purpose.
"I gave evidence to the prison review a few weeks back and I called it an institutionalised malaise," he said.
"When something continues as long as the problems we have in our prisons have continued, it's no longer a crisis, a crisis is something that comes to a head and you recover very quickly."
The mother of one of the three prisoners who took their own life while on remand in a NI prison said she raised concerns about her son's mental state with the Prison Service.
Aaron Hogg, 21, from north Belfast, was awaiting trial in Maghaberry Prison for attempted murder.
His mother, Lyn Edwards, said the system was failing in its duty of care towards her son.
"We had written a letter just saying how vulnerable he was, that he was in their care and it was up to them to look after him," she said.
"There are a lot of people in there with mental health issues who are just put in there, locked up, forgotten about, and that's it.
"The whole system let Aaron down."
The former governor of Maghaberry Prison said high levels of staff sickness mean that on occasion there are not enough wardens to look after inmates out of their cells.
William McKee said staff do their best to give prisoners the appropriate care.
"Within the prison system they try to get the prisoners out of their cells as much as possible," he said.
"They encourage education, handicraft, workshops, but unfortunately within the prison system in NI, you have a very high sick level from staff, which means on occasions, because of the manning levels that the union has agreed, if there are insufficient staff then the prisoners will remain behind doors."
Earlier this month, a 19-year-old man and a 23-year-old woman were found dead in their cells in Hydebank Young Offenders Centre.