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Gruesome images on cigarette packets are being criticised by some smokers as worthless - but researchers say such pictures have been proven to make a difference.
The anti-smoking initiative began yesterday, requiring the images of smoking-affected organs and body parts to be displayed in addition to existing written warnings.
Reactions from the public were mixed.
Associate Health Minister Damien O'Connor said he made no apologies for the tactic to get people to quit the habit that claimed about 5000 lives a year.
One tobacco company says the international research opinion on its effectiveness is mixed.
Massey University marketing professor Janet Hoek said several studies had shown the images made a difference.
In one study, 150 smokers and 150 non-smokers, with an average age in the mid-20s, were asked to consider images such as a dissected brain showing stroke and a mouth with stained and damaged teeth, compared with a text-only health warning.
"The behavioural data showed that the image labels were more effective in encouraging quitting," the study found.
"Smokers' probability of continuing to smoke when faced with these warnings ranged from 73 per cent to 87 per cent - the text-only control was the least effective. Between 25 per cent and 40 per cent of smokers said they would call the quitline or smoke fewer cigarettes, and again the control text-only warning received the lowest behaviour change estimate."
A second study, involving 310 smokers, tested the images against new, updated text-only warnings.
"The results suggested that pictorial warning labels are more credible and effective than the text-only versions, but not more fear-inducing.
"The pictorial warnings also elicited greater quitting intentions, and were perceived as being better deterrents to non-smokers."
Smoking lobby group Ash said the graphic images on cigarette packs in Australia had boosted calls to the nation's smoking quitline by 30 per cent.
