Members of the Irish Prison Officers Association have reiterated the seriousness of overcrowding at Mountjoy Prison and say their lives are in danger.
The IPOA also says it has called for an urgent meeting with the prison service, due to take place next week.
The comments follow the stabbing of a prisoner in the prison earlier today, the fourth violent attack in the space of a week.
The 28-year-old man was serving five years for possession of firearms. He was stabbed four times in his cell.
Up to three prisoners were involved in the attack and a knife has been recovered and passed on to gardaí.
It follows an incident yesterday during which a prisoner was taken to hospital after he approached prison officers in the yard and told them he had been attacked.
He was stabbed once in the back and twice in the arm.
Meanwhile, an inquiry is continuing into the circumstances surrounding the killing of another inmate, Gary Douch, while in custody last Monday.
General Secretary of the IPOA John Clinton said he now fears for the safety of his members.
The Minister for Justice, Michael McDowell, yesterday ordered the placing of inmates who ask to be put on protection in single rooms or cells for at least 24 hours.
