Smokers have been offered what may be the dream way to quit - a low-nicotine cigarette to suck on, plus gum, a patch or a lozenge containing more nicotine.

The theory is that separating the ritual of smoking from the main addictive chemical in tobacco smoke may help break the "psychological addiction" and boost the chances of quitting.

Auckland University researchers have tested the quit-smoking potential of low-nicotine cigarettes among 1400 heavily dependent smokers recruited through the Quitline. They say earlier trials have indicated that low-nicotine cigarettes may help people to quit the habit, but these studies had limitations, such as having too few participants to produce reliable results.

The six-month follow-up check on quitting results in the trial is almost complete and the researchers expect to reveal their findings at a European conference in September.

The participants in the trial, funded by the Health Research Council, were given eight weeks' nicotine replacement therapy. As usual through the Quitline, they were all asked to stop smoking after their quit date.

Half were also given low-nicotine cigarettes for six weeks and were told they could smoke them "if they find they simply must have a cigarette".

Cigarettes in this country contain around 13mg of nicotine on average, according to research published in 1997. The cigarettes used in the trial contain 1.5mg and also have a low tar content.

One of the researchers, Dr Chris Bullen, said yesterday that the idea behind the study was that using low-nicotine cigarettes in addition to nicotine replacement therapy might deal with the psychological addiction associated with smoking, leading to better quitting results overall.

"You receive your nicotine from another source rather than the cigarette. It starts to dissociate the pleasure, the satisfaction, from getting nicotine from a cigarette. It's coming from somewhere else. You are gradually weaning off the cigarettes as a source of nicotine and getting it from somewhere else.

"Also, these low-nicotine cigarettes have a reduced tar content. There's evidence that what's in tar may be addictive."

Dr Bullen said replacement therapy doubled a smoker's chance of quitting on any attempt - boosting it from 5-7 per cent to 10-15 per cent.