An inmate who died after being assaulted by another prisoner at Auckland Prison has been named by police.

He was Blake John Lee, 25, of Rotorua, says Detective Inspector John Sutton.

Police were called to the Paremoremo prison, in north Auckland, at about 3pm on Thursday following reports of an inmate-on-inmate assault.

Lee received serious injuries and died at the scene, says John.

A homicide investigation is underway and a post mortem examination will be carried out.

Corrections chief custodial officer Neil Beales says the prisoner died in the prison yard.

"The alleged perpetrator has been placed on directed segregation in the prison's management unit."

Lee was serving a sentence of seven years and seven months in prison after being convicted of a brutal assault on his partner in 2017.

At his trial, the Crown said Lee held his partner captive at their Rotorua home for hours and beat her.

He also poked at her with a weapon similar to a butter knife as she tried to hide under a bed blanket.

Blake's partner told jurors at his trial that she told him to "just stop".

"I remember, like, just touching my leg just to see, like, why it was wet and, like ... I remember, like, holding my hand up to see why my hand was wet and I noticed it was blood, and so I was screaming that I was bleeding and that's when he went out and called his mum."

Among the woman's injuries were a broken leg and a cut to her ankle.

Lee's partner was eventually able to escape through a window and a neighbour called emergency services.

At Lee's sentencing, a cultural report detailed his background that included an "extremely disadvantaged childhood". He was exposed to violence, drugs and gang culture from a young age.

He went on to become a member of the Mongrel Mob.

Lee unsuccessfully appealed his conviction and sentence.

At the end of it's judgement, the Court of Appeal assessed Lee's prospects for the future.

"...[A]t 25 years of age, Mr Lee is now firmly entrenched in a gang environment and there is no suggestion this is likely to change in the future. His prospects of rehabilitation are therefore low and the risk of future offending is correspondingly high."

Corrections Association president Alan Whitley says he understands the prisoner had been stabbed.

-Stuff/Edward Gay.