"I'm more than happy for you to come to Wanganui and come to a bar and we'll canvass them and survey them and we'll see."
Maori Party MP Te Ururoa Flavell eventually stepped in, saying: "Not every Maori lives in the pub ... there's a hell of a lot more Maori in this country who have actually provided positive feedback on this kaupapa and those are the ones we need to focus on."
The Maori Party was making submissions on a bill that would raise taxes on tobacco and increase the price of a pack of 20 cigarettes to more than $20 in four years.
Mr Mair had earlier pointed the finger at the tobacco industry.
"There seems to have been a lot of emphasis in regard to the terrorists of the Ureweras. From our point of view, the real terrorists in this country are the tobacco companies. These terrorists cause immense death to the scale of 5000 [people a year]."
Mr Peters challenged Mr Mair to prove the figure of 5000 deaths.
But he left the the room soon after, leading to speculation from one MP that he had gone out for a cigarette.
When he returned, Professor Richard Edwards from the University of Otago was asked to provide a science lesson for Mr Peters on smoking-related deaths.
The public health expert said: "This figure was not plucked out of the air. You work out from the increased risk that smokers have of developing conditions like lung cancer.
"You then work out from the prevalence of smoking among people with those conditions what proportion [of deaths] are due to smoking."
Based on this research, 80 per cent of 1200 lung cancer deaths a year had been found to be related to smoking.
A large proportion of bronchitis, heart disease, pancreatic cancer, and cervical cancer deaths were also linked to tobacco.
Mr Peters, undeterred, then asked why Japanese people had high life expectancy when they also had high rates of smoking.
Professor Edwards: "It just goes to show that cigarette smoking is not the only determinant of longevity, and Japanese people would live longer if they didn't smoke so much."
The debate led Green Party MP Kevin Hague to tweet: "This experience of the Finance & Expenditure considering the tobacco excise bill underlines why Govt should have allowed it to go to Health [committee]!"