Police were called into Magilligan Prison, Co Derry, today after the majority of prison officers walked out.
The Prison Service said the walkout was over a dispute about a scheduled routine meeting of the Prison Service Management Board that had due to be held in the prison today.
A Prison Officers Association (POA) branch meeting yesterday passed a motion saying officers would withdraw from their posts for an emergency meeting if any members of the management board set foot in the jail.
Mr Finlay Spratt, chairman of the POA, said their ultimatum was followed by a letter to officers from the governor of the jail saying they would not be paid for today if they did not carry out their duties.
"They withdrew to the mess because they hate the sight of the management board. They had agreed to unlock the prisoners, feed them and provide enough staff for medical and fire watch cover. But the governor said if they did not all work normally they would not be paid, so they have gone home."
The Prison Service said about 90 per cent of the officers had "deserted their posts" and all visit to the jail were cancelled for the day.
Mr Peter Russell, director general of the Northern Ireland Prison Service, criticised the action. "This behaviour is disgraceful. No matter what the point of the dispute there can be no excuse for such dereliction of duty," he said.
He said prison officers had a "duty of care to persons in their charge which they are neglecting".
But Mr Spratt accused Mr Russell of being "arrogant and ignorant" towards his members and warned: "He will never break the will of the Northern Ireland Prison Service. The terrorists have tried for 35 years and failed, he won't manage it."
Last Friday officers walked out of the top security Maghaberry Prison in Co Antrim, forcing police to take over their duties, as part of their continuing dispute with the Government about the provision of security measures at their homes after a spate of terrorist attacks.
PA