The health risks of second-hand smoke remain untested, according to a panel of medical experts at a Tobacco Manufacturers Association (TMA) seminar last week.
Tim Lord, chief executive of the TMA, said that evidence that passive smoking was seriously harmful was not yet conclusive and more research was needed.
He also said that the hospitality industry should be allowed more time to self-regulate on smoking restrictions before legislating.
"Our side of the debate has not been heard," he said. "It has been suppressed by the anti-smoking lobby who want to de-normalise smoking in an attempt to stamp it out altogether."
Dr Christopher Proctor, a former employee of British American Tobacco, advised delegates that any ban was premature because the relative risks of passive smoking were low.
Dr Ken Denson said the idea that environmental tobacco smoke was harmful was a "myth" and "illusory". He also argued that health problems witnessed in smokers were more attributable to unhealthy lifestyle choices such as diet and exercise.
Experts and activists from the anti-smoking lobby did not attend the event. "Taking part in this kind of discussion indicates there is a debate to be had on the harmful effects of passive smoking," said a spokeswoman from Ash. "There isn't."