The Ministry of Health is investigating a survey in which people were offered incentives to test cigarettes.
The survey was set up by Colmar Brunton on behalf of British American Tobacco.
Lobby group Action on Smoking and Health director Ben Youdan says more than two dozen people laid complaints about the survey this week.
Mr Youdan says they had been offered free cigarettes, a $40 incentive and Fly Buy points, in a breach of the Smoke-free Environments Act (1990).
He says the invitation to participate in the survey did not discriminate between smokers and non-smokers.
British American Tobacco says it is disappointed Colmar Brunton did not plan the survey in line with agreed on protocols which stipulate that participants must be existing smokers over the age of 18.
The company will not confirm whether it has paid New Zealanders to test cigarettes before.
The Ministry of Health is investigating, but says any suggestion of a possible prosecution is premature at this stage.
Colmar Brunton says it made a mistake in the wording of its invitation to participate in the cigarette tests and apologises for any offence.
However, it says conducting cigarette tests with existing smokers is an established and legal practice in New Zealand.