Doctors blasted New Zealand’s conservative government on Tuesday for revoking world-leading anti-smoking laws, warning that people will die over the act of "public health vandalism".

The country passed a suite of anti-smoking measures under former prime minister Jacinda Ardern, winning praise as a world leader in the global fight against Big Tobacco.

But public health experts now fear that reputation is in tatters, after incoming premier Christopher Luxon used his first day in office to consign those laws to the scrap heap.

University of Otago tobacco control expert Richard Edwards told AFP a public health "tragedy" was unfolding in the country, which once envisioned becoming almost entirely smoke-free by 2025.

"It was not something that we anticipated, we did not think a government could be so backwards," he said. 

"I was absolutely shocked and appalled. It is one of the worst days I can remember for public health. It is public health vandalism."

Dr Samantha Murton, President of the Royal New Zealand College of General Practitioners, was also critical of the move. 

"We are astounded as to how you could repeal something that has been so widely supported and would prevent the deaths of so many," she said in a statement on Tuesday.

The headline reform was a "generational smoking ban", which would have effectively outlawed the sale of cigarettes to anyone born after 2008.

Other measures would have forced tobacco companies to lower nicotine levels in cigarettes, and slashed the number of stores authorised to sell tobacco products from 6,000 to 600.

"None of those measures have yet been implemented at a national level in any country around the world. They were highly innovative," said Edwards.

"These were going to have a profound effect on reducing smoking. That will all be lost." 

Inspired by New Zealand, a string of countries have been mulling over similar moves to crack down on cigarettes. 

British Prime Minister Rishi Sunak unveiled a remarkably similar "smoking ban" proposal at the Conservative Party conference in October this year.

- 'Disastrous, terrible' -

Edwards said New Zealand was "squandering" a huge opportunity, and had trashed its reputation as a world leader in public health. 

"So many people from overseas are aghast at this action, because they were looking to New Zealand to lead on this. 

"It has global implications. It is a disastrous, terrible move." 

New Zealand has a relatively small number of adult smokers, but tobacco-related disease has exacted a particularly heavy toll on the country's Indigenous Maori population. 

Maori women have some of the highest lung cancer rates in the world, according to advocacy group Smokefree Aotearoa. 

Experts are baffled at the incoming government's change of heart, with smoking barely mentioned as an issue during the recent general election campaign.

Some have suggested the government wanted to boost its coffers with the tax revenue promised by cigarette sales.

For his part, Luxon has said a cigarette ban would have created a flourishing and untaxed black market.

Asthma and Respiratory Foundation chief executive Letitia Harding said Luxon's reasoning defied logic. 

"The argument that a bigger black market could emerge is an argument that is used by big tobacco companies," she said in a statement on Tuesday.

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