The Northern Ireland Prison Service has been branded a fiasco by the body which represents rank and file officers.
Finlay Spratt, chairman of the Prison Officers' Association (POA), launched a stinging attack on recent reforms during an appearance before a Stormont scrutiny committee.
It was claimed staff levels have been decimated while a punishing new rota system has left others facing burnout.
Mr Spratt told MLAs: "The prison service, as far as we are concerned, at the minute is a disaster."
He said staff morale remained low and that new recruits, being paid half as much as "old hands", were "being thrown in at the deep end".
"The people who manage the Northern Ireland Prison Service have made a complete horlicks of it," added Mr Spratt.
Particular concerns were raised about Maghaberry jail which was branded the UK's most dangerous facility in a damning report last year.
HM Inspectorate of Prisons and Criminal Justice Inspection Northern Ireland (CJINI) said the high security facility near Lisburn in Co Antrim, was "a prison in crisis", with "unsafe and unstable" conditions.
The POA said Maghaberry was having to operate with a shortage of 97 prison officers and that up to 100 others were absent on sick leave.
Just two officers are charged with overseeing 50 male inmates, the committee heard.
Ivor Dunne, who represents the men and women who work the landings in Maghaberry, said he feared that someone could be killed or that a female officer may be raped.
He said some members felt so stressed they were resorting to self harm or were experiencing marriage difficulties.
During the final three months of last year, so-called "discipline alarms", sounded when an officer feels under threat, were pushed 378 times, it was revealed.
In the same period, 64 assaults and 11 attempted assaults were carried out in Maghaberry - 13 of them against prison officers.
T h e figures do not include being spat at; having the contents of a pot thrown at them; or being threatened, MLAs were told.
DUP MLA Alastair Ross, chairman of the justice committee, said the concerns were being taken seriously.