Police Minister Judith Collins has been challenged in Parliament over police officers' use of a false drink-drive checkpoint to target elderly euthanasia advocates.

Collins repeatedly said today she was unable to comment on the controversial checkpoint because the officers' actions were under investigation.

Police have referred themselves to the Independent Police Conduct Authority (IPCA) over the matter, in which officers used a booze bus to collect details about people who attended an exit international meeting in Lower Hutt last month.

Act Party leader David Seymour, who wants voluntary euthanasia to be legalised, challenged Collins on the officers' actions during Question Time in Parliament today.

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"Does she believe the public have a right to be concerned about police conducting roadside breath screening tests with the intention of collecting personal information for investigations unrelated to road safety?"

Collins said she was prevented by the Policing Act and the Cabinet manual from intervening in police operations.

"This is not a matter I can comment on. It is currently with the IPCA and for me to make a statement about that or have any sort of view would in fact actually try to influence the IPCA investigation."

That prompted Labour MPs to shout across the debating chamber that the Government was "stopping old ladies".

Seymour questioned the use of police resources to target "law-abiding people attending a peaceful meeting" in light of figures released yesterday which showed burglary rates had risen.

Collins reiterated that she was not going to "wade into [the IPCA's] investigation".

The IPCA has also received three complaints from the public about the fake police checkpoint.