However, a spokesman for the Corrections Association of New Zealand told the Herald he understood the prisoner had been beaten severely with a broom.
Christchurch Men's Prison director John Roper confirmed that a prisoner had been assaulted by a fellow inmate.
"The victim has been hospitalised and is receiving medical treatment.
"Corrections manages some of New Zealand's most difficult and challenging citizens," Mr Roper said.
"Violence in prison is not tolerated and any prisoners who use violence will be held to account."
CANZ industrial officer Beven Hanlon said he had initially been told an inmate had been stabbed.
"But I then got contacted from someone afterwards saying actually that wasn't the case - but that he was attacked with a broom.
"He was beaten quite badly and that he was now in hospital,'' he said.
"One [inmate] came up behind him with a broom, beat him, knocked him to the ground and continued to beat him until staff stopped him. I understand that he's not in a good way. That's how it's been put to me - it's pretty serious.''
Mr Hanlon said the incident again highlighted the need for prison guards and prison officers to be better equipped in the job.
Although guards wore heavy-duty vests, they were not allowed to carry pepper spray - something Mr Hanlon said was something that could hugely assist guards facing a dangerous situation with a prisoner.
Prison director for Christchurch Men's Prison, John Roper, confirmed that a prisoner had been assaulted by a fellow inmate.
"The victim has been hospitalised and is receiving medical treatment.
"Corrections manages some of New Zealand's most difficult and challenging citizens. Violence in prison is not tolerated and any prisoners who use violence will be held to account,'' Mr Roper said.
