About 100 people protested outside a gun buyback event in Henderson, West Auckland on Saturday.

Police are scrambling to identify how many people accessed the personal details of thousands of gun owners in a data breach.

The details of more than 37,000 firearm owners, including the guns they possess and bank account information, were able to be accessed in the breach, according to the Council of Licensed Firearms Owners (Colfo).

The gun lobby group said it had received the data from a supporter and has released some images obtained in the breach, with personal details redacted.



At a press conference on Monday evening, Police Deputy Commissioner Mike Clement confirmed the data was available to a select group of gun dealers since November 27.

MONIQUE FORD/STUFF Police Deputy Commissioner Mike Clement speaking on gun buyback database breach on Monday evening.

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A gun dealer raised the alarm after finding they could access the data.

Clement said this was the only person confirmed as accessing the data, though Colfo has said multiple people gained access.

The breach occurred after an external software developer, German company SAP, updated the system in a way which hadn't been authorised by police, Clement said.

He said police were working with SAP to determine how many people accessed the data.

STACY SQUIRES/STUFF A possible privacy breach has troubled police's gun buyback scheme.

He said he could not give an "ironclad" promise the data had not spread further.

"We will work pretty fast ... to make sure that if there has been any any use of the information that we're aware of it and we can go to those people," he said.

He said prosecution was a possibility if the private information was distributed, but the images published by Colfo did not meet this threshold.

Many firearm owners contacted Stuff expressing their dismay at the data breach.

Clement said they could still trust the gun buyback system, and did not need to be concerned about their security as a result.

COLFO/SUPPLIED The Council of Licensed Firearm Owners has released images obtained through a privacy breach of police's firearm buyback scheme.

"We're taking this very seriously ... We've got a situation today that I'm not happy with, I can assure you. So in that sense, some of them might feel let down.

"But the reality is, we've worked extremely hard with the firearms community from the outset with regards to the process."

Police Minister Stuart Nash, speaking at the weekly post-Cabinet meeting press conference, said the data was not publicly accessible, and he had made clear to police the source of the breach must be identified quickly.

"Police will hold people to account if information has been assessed and shared unlawfully."

The breach did not demonstrate the buyback scheme had failed or needed to be re-evaluated, he said.

Firearm owners who have had semi-automatic firearms and other guns banned following the March 15 terror attack have been asked to notify police of their weapons through an online form.

COLFO/SUPPLIED The Council of Licensed Firearm Owners has released this redacted image showing the personal information made publically available through what police have confirmed was a "potential privacy breach".

Colfo, in a statement, said several of the group's supporters had taken screenshots and downloaded information 37,125 licensed owners and the details of 280,000 prohibited firearms and parts.

A firearm owner had notified the gun lobby group after attempting to update their own information on the site and discovering a list containing the information.

Another person had downloaded the data and provided it to Colfo, she said.

The information's availability meant firearm owners had become "potential targets for criminals", McKee said.

"This is a failure, this is the ultimate failure of the system of not only registration, but of the [buyback] system that's been run. We have been asking for it to be slowed down."

ROBERT KITCHIN/STUFF Firearm owners who have semi-automatic firearms banned after the March 15 terror attack have been asked to notify police of their weapons through an online form.

The Government has promised to bring in a firearm register for all guns, to be managed by police.

National Party police spokesman Brett Hudson said Nash needed to take responsibility for the breach.

"His Government put the buy-back scheme together. It has failed to protect New Zealanders' private and very sensitive information.

"How can New Zealanders have confidence in the firearms register the Government is proposing when they can't even protect their personal details in their buy-back scheme?"

RICKY WILSON/STUFF A Government-run gun buyback scheme is nearing completion, with a December 20 deadline for semi-automatic firearms to be handed in looming.

ACT leader David Seymour said the police minister "must resign" over the data breach and the Government should back down from a planned registry of all firearms.