New Zealand's government will slash the number of retailers selling cigarettes and prevent Kiwis born from 2011 onward from ever buying tobacco as part of its ambitious Smokefree 2025 plan.

It will be an offence to sell or supply smoked tobacco products to anyone aged 14 or under when legislation kicks in from 2025.

Nicotine content will also be weakened under plans announced in parliament on Thursday by associate health minister Ayesha Verrall.

"Smoking is still the leading cause of preventable death in New Zealand and causes one in four cancers," she said.

"We want to make sure young people never start smoking ... people aged 14 when the law comes into effect will never be able to legally purchase tobacco."

The government has pledged to "significantly" reduce shops that can sell smokes, "especially in low-income communities", believing smoking to be a key factor in life expectancy gaps.

Dr Verrall said non-Maori live on average eight years longer than Maori New Zealanders, and 2.5 years of that gap was attributed to smoking.

"We want to make sure young people never start smoking ... if nothing changes it would be decades till Maori smoking rates fall below five per cent, and this government is not prepared to leave people behind," she said.

While 13 per cent of New Zealanders smoke, the figure jumps to 31 per cent of Maori New Zealanders.

The Smokefree 2025 goal - which is to limit smokers to five per cent of the population - was adopted in 2012 under John Key's National government, though the current opposition is yet to reveal whether it supports the plans.

Ascendant right-wing minor party ACT ripped into the changes, saying "prohibition has never worked".

"We will end up with a black market for tobacco, with no standards or regulation, and people will be harmed," spokeswoman Karen Chhour said.

The Greens have hailed the "bold" policies, as have public health campaigners.

Like many countries, NZ has adopted a number of health measures to curb smoking rates, including tax hikes, advertising bans and anti-smoking campaigns.

They have worked but the government still has a way to go to reach the five per cent goal by 2025.

At the turn of the century, one-in-four New Zealanders smoked.

That fell by half to one-in-six by 2012, when the Smokefree 2025 goal was adopted, and again to one-in-eight by 2019.

The five per cent goal has been reached for year 10 students, down from 28 per cent in 2000.

Speaking across Wellington later on Thursday, Prime Minister Jacinda Ardern put the need for an action plan into context.

"Half of those who take up smoking die from its effects," she said.