New Zealand imposed a ban on assault weapons Thursday, moving swiftly following the Christchurch massacre and triggering renewed calls from leading American politicians for gun controls in the United States.

New Zealand's Prime Minister Jacinda Ardern leaves after the Friday prayers at Hagley Park outside Al-Noor mosque in Christchurch, New Zealand March 22, 2019. (Photo: VCG)

Prime Minister Jacinda Ardern said assault rifles and semi-automatic weapons were now banned with immediate effect, making good on a pledge to the country of the military-style weapons used in last week's slaughter of 50 people.

The killings at two Christchurch mosques by an Australian white supremacist have caused national soul-searching over New Zealand's lax gun laws.

But the crackdown promises to have political repercussions beyond the country's shores, including in the United States where gun control is one of the most divisive national political issues.

"In short, every semi-automatic weapon used in the terrorist attack on Friday will be banned in this country," Ardern said.

She added that high-capacity magazines and devices similar to bump stocks -- which allow users to fire weapons faster  -- will also be banned.

New Zealand's ban includes interim measures to prevent a run on such guns before legislation is enacted, and outlawing weapons already in private possession.

Guns are to be handed in and destroyed via a buyback scheme that will cost between Nz$100 million and $200 million (between US$69 million and $139 million), depending on how many are received and their valuations.

- A changed nation -

NZ Police Commissioner Michael Bush said there were around a quarter of a million firearms users in New Zealand, but he did not  give a breakdown on how many possess semi-automatics.

Conservative estimates indicate some 1.5 million weapons are in circulation in New Zealand, equating to three guns for every 10 people, well below the US ratio of more than one weapon per person.

"The vast majority of New Zealanders will support this change. I feel incredibly confident of that," Ardern said.

Simon Bridges, leader of the opposition National Party, embraced the ban and pledged to work with the government on it.

"The terrorist attack in Christchurch last week has changed us as a nation," Bridges said.  

"We agree that the public doesn't need access to military-style semi-automatic weapons."

Initial public reaction was positive in the still-shocked country, where hundreds of people turned out for a second day for sombre funerals in Christchurch.

"It's a good thing. Why would we need to have guns like this in our houses?" Kawthar Abulaban, 54, who survived the shootings, told AFP.