Six months after the Christchurch mosque shootings, which Ms Ardern said "forever changed" her county, the government has unveiled a massive crackdown designed to prevent any repeat.

Kiwis will be asked to register every firearm their own, renew their licence twice as often, and could face hikes in licensing costs.

Shooting clubs and ranges will also be subject to a new licensing regime, dealers will be asked to pass new suitability tests and doctors will also need to report mental health concerns of gun owners to police.

Ms Ardern said she viewed the changes as "fair and reasonable".

"I absolutely recognise there is legitimate need in our community, particularly our rural community to access guns," she said.

"This is about ensuring people who need to access guns can, but those who shouldn't don't.

"And also, trying to prevent guns moving into the black market, and from being used illegally."

New Zealand will also accede to a new United Nations firearms protocol and implement greater border controls over gun imports.

Punishments for firearm-related offences will also balloon.

The maximum penalty for supplying a firearm to an unlicensed person will rise from a jail term of three months and a fine of $1000, to two years and $20,000 respectively.

Police Minister Stuart Nash said implementation of a new "warning flags" system, including the raising of extremist views, might well have stopped the March 15 massacre.

"The 'fit and proper' (person) test is being tightened. He may well have been caught under that," he said.

"The alleged terrorist was stockpiling ammunition and guns. That would have raised a flag.

"What we're also doing is licensing gun clubs. That may well have also raised a flag."

While Kiwis are yet to pass judgment on the measures, the opposition National party has previously flagged their dissatisfaction.

Opposition Leader Simon Bridges has shown his skepticism of gun registries and whacked the police's gun buyback for failing to attract enough weapons.

The bill doesn't require opposition support to pass parliament, but Ms Ardern has appealed for it.

"Our hope all the way through is that we would have cross-party support for something as significant as our gun laws," she said.

"These changes are focused on public safety. They're a response to what we believe New Zealanders have asked for."

The gun law reforms will be tabled in parliament later this month.

Australian Associated Press