New Zealand Police have admitted targeting pro-euthanasia campaigners in a drink-drive checkpoint.

The move has been branded an "abuse of power" and "deeply un-Kiwi", and a complaint has reportedly been laid with the Independent Police Conduct Authority (IPCA).

This afternoon, police confirmed officers had used a breath-testing checkpoint to target people attending an Exit International euthanasia meeting in Lower Hutt earlier this month.

The officers were investigating a suspected self-inflicted death, and reportedly asked the coroner to put its investigation on hold while they carried out a criminal one.

Inspector Chris Bensemenn confirmed this afternoon that the checkpoint was set up close to where the meeting was being held in Lower Hutt with the purpose of "identify[ing] people attending an Exit International meeting".

"Police have a duty of care and a responsibility to the community to investigate any situation where we have reasonable grounds to suspect that persons are being assisted in the commission of suicide," he said in a written statement.

"Police are responsible for enforcing New Zealand's laws, and currently suicide or encouraging/helping someone to commit suicide - is illegal in New Zealand."

Suicide is not illegal or considered a crime in New Zealand, but assisting or encouraging someone to take their own life is.

The Health Select Committee is currently conducting an inquiry into assisted dying.

Bensemenn said information gathered through the checkpoint had "enabled police to provide support and information, to those people who we had reason to believe may be contemplating suicide".

"The timeliness and appropriateness of this support and information was an important consideration undertaken by police in planning this operation."

Euthanasia was a "very sensitive issue", he said, but the actions of officers had been "carried out in good faith".

Barrister Michael Bott said the actions of officers involved in the checkpoint was "an abuse of police power".

"It's a completely improper use of the stop and check power," he said, which was limited to matters such as driver licensing, breath-testing, and checking registrations details.

"What they're doing is using this power as a cloak to undertake surveillance and to stop and ascertain private details and particulars of people attending a public meeting."

The majority of those attending meeting were pensioners, he said, and would likely have found it "quite frightening and disturbing" to have police officers on their doorsteps following a routine drink-drive check.

"And it doesn't seem to be good grounds or reasonable cause to suspect or believe an offence is being committed or about to be committed," Bott said.

"The mere fact that you attend an Exit meeting, which is probably a political meeting or a meeting that imparts information, doesn't mean that you support of endorse the group at all, so you need more information than that."

Such actions from the police could be viewed as having "a chilling or fettering effect upon your rights", he said, likening such surveillance to something "you might see in Frank Bainimarama's Fiji as opposed to suburban Lower Hutt".

"It appears to be some kind of moral crusade driven from someone on top to stop people going to a public meeting to learn about Exit and their goals."

Checkpoint 'may be illegal' - ACT

Act Party leader David Seymour said the behaviour could be illegal, and was "at best, dodgy".

"People have the right to meet and discuss issues without fear of police harassment," he said.

"The admission that the police used a drink-driving checkpoint to obtain the identities of people attending a meeting is deeply un-Kiwi.

"The police are given the power to set up checkpoints to combat drink driving, we do not give them powers for one purpose so they can abuse them for another."

He likened the checkpoint to interrogating peaceful citizens "under false pretences".

"This is, at best, dodgy behaviour from the police or their superiors, but may also be illegal," Seymour said.

"Human rights lawyers have already raised concerns that it breaches the Human Rights Act.

"There is then the question of motive. Who was pushing for this surveillance, what was their motivation, and why were the Police Minister and Solicitor-General not aware of such a politically sensitive operation?"

Somebody had to be accountable for the police's actions, he said.

"If these individuals were responsible then they must be answerable, they cannot hide behind the usual excuse that it's 'police operations'.

"People expect police resources to focus on real crimes, not to treat members of advocacy groups like gang members."

A spokeswoman for Police Minister Judith Collins said the case was an operational matter for police, and directed all questions to the force.

The admission from Bensemenn comes just weeks after police raided the homes of elderly women in Wellington and Nelson, sparking accusations of political interference with long-time euthanasia campaigners.

The raids smacked of interference into the current parliamentary inquiry into assisted dying, Voluntary Euthanasia Society president Maryan Street said at the time.

- NZ Herald