A prison officer remains in an induced coma following an attack at Rimutaka Prison yesterday.
The guard was hospitalised with serious head injuries after he was assaulted by a group of prisoners when he went to the aid of a prisoner who was being assaulted.
The Corrections Department says the guard is in a serious but stable condition and ONE News understands he has a fractured skull.
Meanwhile, the inmate who was also hospitalised with minor injuries is back in jail.
The Corrections Association says if the officer, who has 17 years experience, had had pepper spray the outcome would have been different. The union wants prison officers to be treated like the police and also have access to Tasers.
President Beven Hanlon said more than two years after an officer died from serious head injuries sustained in a prisoner attack they are "still walking the landing with nothing but our wits and a cotton uniform".
"It is time our safety was taken seriously. It is one thing to keep investigating these incidents and charging prisoners for attacking staff but that is little comfort to the family and friends of these injured staff," Hanlon said.