New Zealand's Prime Minister Jacinda Ardern has vowed to change the nation's gun laws after confirming the "primary perpetrator" in Christchurch's terror attack used five weapons.

"I can tell you one thing right now, our gun laws will change. There have been attempts to change our laws in 2005, 2012 and after an inquiry in 2017. Now is the time for change," Ms Ardern told reporters in Wellington on Saturday morning.

Two Australian gun law experts have welcomed the tightening of New Zealand gun laws.

Rebecca Peters, who was the chair of Australian National Coalition for Gun Control at the time of the Port Arthur massacre in 1996, said New Zealand had the opportunity to tighten its gun laws at the same time but did not.