Prime Minister Christopher Luxon says he has spoken to his team about fact-checking, after he wrongly claimed smokefree legislation would mean only one store selling cigarettes in Northland.
He says the new government is "deeply committed to lowering smoking rates in New Zealand".
National's coalition agreements with New Zealand First and ACT include plans to repeal legislation which would have restricted the sale of tobacco to anyone born after 2009 and the phasing in of low-nicotine cigarettes.
Labour's health spokesperson Dr Ayesha Verrall accused Luxon of misleading the public after he wrongly said there would only be one tobacco outlet in Northland under the legislation. Documents from the director-general of health showed there would be 35.
Luxon told Morning Report on Monday his team got the numbers wrong and they had been spoken to about fact-checking their information.
"Our team meant to say one outlet... in a town across Northland but we got it wrong. What I've said is look, we got that wrong. We've spoken to our team about making sure that we are fact-checking all of our information before we go off with statements and actually are they... supported."
Luxon said they wanted to ensure there were really robust processes in place.
The bigger point, he said, was "concentrating distribution into 600 outlets across New Zealand will mean that there will be towns that will have one or two outlets only".
"We do believe that that will become a massive magnet for crime and we also believe that it will drive more of the market into the black market as well."
There was a massive increase in retail crime and ram raids under the previous government, he said.
Speaking to reporters ahead of Labour's caucus meeting on Monday morning, Verrall said no piece of advice had ever claimed there would be just one store selling cigarettes in Northland.
"No. That's absolutely ludicrous and shows that the National Party has not been engaging on this issue in a responsible way. This is more than a matter of how you sort out what lines you say to the media. It is a public policy issue that we are debating in New Zealand. The number of stores in the Smokefree Act matter, surely you would have had the facts before you formed such a strong opinion on them."
Labour's leader, Chris Hipkins, said he was not surprised by National's error.
"A number of the bold assertions that they were making on the campaign trail also didn't stand up to scrutiny, I mean I think this is a government that is clearly going to be playing fast and loose with numbers and actually they need to sharpen up, they are the government now.
"Big picture, when you're the government, you need to make sure your numbers add up. The National Party don't seem to have been able to do that on the campaign trail, it's unacceptable for them to do that now they're in government ... that is their core job."
He said it put National's proposed tax cut package into question, too.
"The National Party for the last probably four years or so have been saying 'tax cuts are affordable, tax cuts are affordable, tax cuts are affordable', they're now saying that to pay for those they want more New Zealanders smoking. I think that just shows that what they were saying all along wasn't true."
A group of Northland doctors have written to Health Minister Dr Shane Reti to voice their concerns about the plan, saying it was anti-health.
Asked what he had to say to health professionals who had concerns about the repeal, Luxon said his government would be continuing efforts to lower smoking rates.
Smoking rates had declined in the past 30 years, he said.
Asked if he had evidence the government's plan would stop as many people smoking as the status quo, Luxon said: "I'm not sure that the previous Labour government's approach had a guaranteed model of how it would reduce [rates]."
Verrall said she thought the government had underestimated how important the smokefree laws were to the health system and the public's support for them, and was hopeful they would back down.
"What we've seen from this government in relation to smokefree is an effort to cast doubt on regulations which are evidence-based and have been shown through that modelling to save lives. It is underestimating the intelligence of the New Zealand public. We all know what's going on here."