An inmate who was stabbed in the chest in Rimutaka Prison is still in hospital nearly a month after the attack.
A Corrections spokesperson said in a statement a prisoner was taken to hospital on April 28 after an "alleged assault" at the prison in Upper Hutt.
"The area in which the assault took place was secured as a crime scene and all evidence was provided to police, who are investigating. Corrections is also carrying out a full investigation into the incident."
Corrections said the prisoner was still going through treatment and recovery in hospital, but would not say what condition he was in.
"Following the incident two prisoners were placed on directed segregation and moved to the prison's management unit."