Four police officers beating a young man with batons and pepper-spraying him 65 times was "unnecessary, unreasonable, and unjustified", the Independent Police Conduct Authority has found.

The authority today released its findings on the conduct of Whakatane Sergeants Keith Parsons and Erle Busby, Constable John Mills and Senior Constable Bruce Laing during an incident in 2006.

Rawiri Falwasser, 26 at the time, had been arrested in Edgecumbe on the suspicion of stealing a car.

He was put in a holding cell at Whakatane police station, where he refused to give his fingerprints and sign a form that he had been told of his rights under the Bill of Rights.

As police officers tried to move Mr Falwasser to another cell, he was struck several times with police batons and repeatedly pepper-sprayed.

The officers armed themselves with riot shields and Mr Falwasser received a 6cm cut to his head.

He later said he could hardly breathe from all the pepper-spray in his cell. His vision was blurred, and he felt as if his face was burning. For several weeks after the incident, he suffered from headaches and dizziness.

The authority's chairman, Justice Lowell Goddard, said the investigation found the use of force unjustified, and the type of force unnecessary and unreasonable.

"There was no urgent need to move Mr Falwasser. He should have been left in the holding cell till he had calmed down and agreed to provide fingerprints. The use of an escalating and inordinate amount of pepper spray simply exacerbated the situation," Justice Goddard said.

The police officers were charged for nine charges of assault and acquitted by a jury in 2008.

Mr Falwasser received $30,000 in compensation after a High Court ruling earlier this year.

The IPCA reached the following conclusions:

* The conduct of the police officers who dealt with Mr Falwasser was unnecessary, unreasonable, and unjustified.

* The subsequent police investigation was professional and thorough and independent advice was properly obtained.

* The police decision to lay criminal and disciplinary charges against the officers was justified and appropriate.

The authority also endorsed:

* The findings of the Police Disciplinary Tribunal that the actions amounted to misconduct for the officer who chose to be dealt with under that option.

* The submission of Counsel for the Attorney General that "the New Zealand Police had done everything within its power to investigate, acknowledge, condemn and ensure accountability for those officers involved in the use of excessive force against Mr Falwasser", reached during civil action brought by Mr Falwasser.