The police watchdog has found authorities shouldn't have tried to speak to a man who earlier declined to speak them.

Photo: RNZ / Richard Tindiller

A police officer stopped and questioned two men in Herne Bay in Auckland at about 2.30am on 16 May 2018 while patrolling the area following a sexual assault a week prior.

After initially answering the officer's questions, one of the men decided not to engage further and walked to his nearby home in an accommodation complex.

Other officers were then instructed to go to the address and talk further to the man.

Although the man had told the night manager he did not wish to speak to police, the night manager allowed the officers to enter the communal area.

Police then intervened in a physical altercation between the man and the night manager. The man pushed a police officer in the chest and was subsequently unlawfully restrained and handcuffed the man.

The Independent Police Conduct Authority reviewed the incident and found police should not have gone to the man's address to question him further.

"It was appropriate for the first officer to question the two men on the street. However, their engagement with police was voluntary and both were entitled to stop talking to the officer and leave.

"The officers who subsequently visited the home of one of the men to question him further acted unlawfully," IPCA chair Judge Colin Doherty said.

Police have implied consent to be at the supported accommodation facility and also express consent from the night manager.

But they should not have attempted to speak to him when it was known he did not want to engage, Judge Doherty found.

Relieving District Commander for Auckland City Superintendent Bruce O'Brien said there was no doubt the officers were working hard to patrol the area following a serious sexual assault with the offender responsible still not identified or located.

"The staff had great intentions but we acknowledge that the person involved did not have to continue speaking with police and going to the address to speak with him could have been handled differently."

He said the police had since met with the man and his family and apologised.

Questioning members of the public

The ruling made special note of the police ability to question the public.

It stated: "If an officer asks a member of the public for information, it is generally up to the person to decide what information, if any, to provide. Police do not have a general power to require a member of the public to answer questions, even if the person has been arrested.

"In certain circumstances, Police do have authority to require a person to provide information: a) the name, address and date of birth of the driver of a vehicle that has been stopped by Police; and b) the name, address and date of birth of a person they believe is committing an offence relating to the sale of alcohol."