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Convicted murderer Graeme Burton will "definitely" kill again unless he is taken out of circulation, says the leader of the country's prison officers organisation.

Corrections Association president Beven Hanlon said Burton, who allegedly stabbed a gang member in Auckland's maximum security Paremoremo Prison yesterday, was so dangerous he should be kept in restraints and not allowed to associate with other prisoners.

"He is most definitely a danger. He's killed someone less than two years ago and now he's associating with other prisoners. It's disgraceful. When he gets bored with us, he will have a crack - no doubt about it."

Hanlon said he had spoken to prison officers involved in the incident at about 10.30am yesterday. He said Burton had attacked the prisoner, believed to be Headhunters gang member Dwayne Marsh, on a landing shared by 12 others.

Hanlon said one officer went in unarmed to tackle Burton with no protective clothing and probably saved Marsh's life.

"Burton just went for it and attacked the guy. He stabbed him in the arms and legs and chest. The guard went in while Burton was stabbing the guy and stopped him. He went in while he was in the process of killing someone, just in his cotton shirt.

"Initially they thought it was just another stabbing, but when the guy collapsed they knew it was serious."

Marsh was rushed to Auckland Hospital's emergency department by ambulance and was in the Intensive Care Unit last night.

Hanlon said it was unclear what weapon Burton had used in the attack.

"It could be anything, it could be his toothbrush. I'm picking it could be a plastic knife or fork, sharpened on concrete."

Hanlon said the association had been campaigning for the "heavy duty" eating utensils to be banned after a prison guard was stabbed earlier this year. The guard is still off work recovering.

Burton was sentenced to life in prison in 1992 for the murder of Paul Anderson in Wellington.

He was released on parole in July 2006 but sentenced to preventive detention with a minimum non-parole period of 26 years after fatally shooting Wainuiomata father-of-two Karl Kuchenbecker in January 2007.

Police are investigating but would not be drawn on any details.

The Department of Corrections' Auckland manager Wayne Cummins confirmed an inmate was "seriously injured" in the east division of the prison.

"Although full details of the incident have not yet been established, it appears that a prisoner attacked another prisoner using a makeshift weapon. No staff were involved."

Cummins said the east division of the prison had been locked down and would remain so while staff and police investigated.

The Herald on Sunday understands a major search for drugs, cellphones and weapons will be carried out today.

Cummins said his department was co-operating fully with police and would not tolerate such behaviour.

A source told the Herald On Sunday Burton's mental health had been deteriorating, and he had been hearing voices.

He said there were two groups of rival prisoners at Paremoremo and Burton was growing convinced he was being targeted for a hit.

The source said a go-between tried to convince him he was wrong, but an influx of drugs into the prison over the past few weeks had seen Burton's mental state worsen.

The source said Burton was incredibly fit, despite the artificial leg he needed after being shot during his arrest last year.

Hanlon dismissed claims about Burton's mental health and said there was a possibility he had carried out a "hit" on the leader of a rival gang.

"He is a very cunning and logical person. He's not mad, just bad."

Hanlon described Burton as an "animal" and said he should be held in restraints, separate from other prisoners, and only let out to exercise alone.

"Unfortunately it's just a matter of time before a guard gets attacked. It's an utter disgrace that staff are put at risk like this."

Cummins said prisoners housed in the east division were "the most violent and volatile" in New Zealand.

"Staff are continually searching cells for makeshift weapons and other contraband, however many of these prisoners are adept at fashioning weapons out of everyday items."

A source said Corrections had been trying to get Burton into a secure unit of Auckland's Mason Clinic for mentally ill offenders, but the clinic didn't want him.

Mason Clinic director Sandy Simpson said he did not know of any application by the prison to have Burton transferred but would need to check.

He said there was a waiting list of people to enter the clinic.

Simpson said there was a memorandum of understanding between Corrections and the Ministry of Health on transferring people from prison to mental health treatment. Decisions were made jointly between prisons and the clinic.