New Zealand smokers are exposed to much more nicotine from cigarettes than are Australians, possibly because of a preference for high-nicotine brands on this side of the Tasman.

The results come from a tobacco industry study, which also found New Zealand smokers are exposed to the greatest average amount of tar out of 5703 smokers in eight countries.

Nicotine is the addictive part of tobacco smoke, and tar is an irritant thought to be a major cause of lung cancer.

New Zealand researchers are lobbying MPs to make tobacco companies cut the nicotine level, eventually to the level where tobacco will not be addictive.

The study by international company British American Tobacco's researchers in Britain tested 80,000 butts supplied from smoked cigarettes by smokers in eight countries. Fifteen cigarette brands were tested in each country, to reflect the range available.

The study was published online by the journal Regulatory Toxicology and Pharmacology.

New Zealand smokers sucked out 1.62mg of nicotine a cigarette, the second-highest amount and far more than Australians' 1.36mg.

The variations between countries partially mirror the differences in the amounts of nicotine sucked out of cigarettes in each country in research using smoking machines.

This may in part reflect different kinds of tobacco leaf used at different factories. But this is unlikely to account for the transtasman disparity because much of New Zealand's tobacco supply comes from factories in Australia, although one factory still operates in Wellington.

Christchurch public health specialist Dr Murray Laugesen said yesterday Australian smokers' lower nicotine exposure might be due to their greater preference for lower-nicotine brands, or because New Zealanders might be "sucking cigarettes more intensively".

The Commerce Commission in 2008 established a voluntary approach to removing the adjectives "light" and "mild" from tobacco packaging, after tobacco control campaigners complained that they implied a safer form of smoking when all tobacco smoking was harmful.

The terms have generally been replaced by colour differentiation on the packaging or new descriptive words.

Dr Laugesen said New Zealand smokers being at the top end for nicotine exposure suggested smoking was more addictive in this country.

"It's all consistent with the problems we have. The findings, compared with Australia, show we are not reducing our smoking quite as fast, yet we are spending a lot of money on providing smokers with medicinal nicotine."

The nicotine disparity might also help to explain the New Zealand findings that a quarter of young smokers showed signs of addiction after smoking just one cigarette, and that 80 per cent of smokers regarded their smoking as an addiction.

Dr Laugesen urged the Government to implement radical measures to end smoking within a decade.

These included a tax based on the nicotine content of tobacco and progressive cuts in nicotine levels.

He cited an Otago University survey which showed 85 per cent of smokers wanted the addictiveness of tobacco reduced.

The nicotine content of tobacco is not regulated in New Zealand, although the Smoke-free Environments Act permits the Government to make regulations to control tobacco's "harmful constituents".

Associate Health Minister Tariana Turia, who has responsibility for tobacco policy, said last night: "I'm looking at a range of issues ... and nicotine reduction is one of them."