The tobacco industry has "deliberately deceived" the public with low tar and light cigarettes, which are just as unhealthy as other brands, a report said today.
The Tobacco Control journal claimed that it had seen industry documents showing that companies recognised that low tar products were as dangerous as regular cigarettes, yet marketed them as healthy alternatives.
The authors of the report, which include Dr Richard Pollay of the University of British Columbia, said that some types of cigarettes, including menthol or loosening filter cigarettes, actually delivered more tar and nicotine than unfiltered cigarettes.
"Virtuous brand names and descriptors," such as "Mild", "Ultra", "Light" and "Superlight" were also used to convey a healthy image, he wrote.
However, a spokesman for Philip Morris, the world's biggest cigarette maker, said that the company had never tried to mislead consumers, who were aware that smoking is bad for them.
"There is no such thing as a safe cigarette, the word light is simply describing the taste," Philip Morris said.
A separate study published in a supplement to Tobacco Control also claimed that Philip Morris knowingly marketed cigarettes with defective filters for 40 years.
The "defect" was identified by the authors from the Roswell Park cancer institute in Buffalo, New York.
They trawled industry papers and scientific and medical databases dealing with "fallout", a term coined by the company to describe the debris they said is released from a filter during smoking.
The authors, including Dr John Pauly, believe the "defect" is due primarily to the high speed of the manufacturing process - 250 cigarettes a second.
A collection of memos from the early 1980s details the results of tests to count and size the fallout. Particles were "too numerous to count" the authors said.
The filter "defect", say the authors, is universal and widespread, and is not restricted to a particular brand or type of cigarette.
A third study claims the tobacco industry failed to keep its promises to inform the public of the health effects of smoking, even though its own scientists doubted the safety of cigarettes.
Internal memos and reports show that some senior industry scientists and executives knew about the cancer risks of smoking as early as the 1940s, according to one of the authors, Professor Michael Cummings of the Roswell Park cancer institute.
Yet the industry continued to reassure the public and its stockholders, denying that smoking was harmful right up to 1999, he said.
A spokesman for Philip Morris said: "This isn't new news. It has long been known that particles can become dislodged from filters. Indeed, this issue was the subject of a public lawsuit filed seven years ago in Texas, featuring Dr Pauly, the author of the Tobacco Control article.
"The court dismissed the case and held that Dr Pauly was not qualified to testify about the effects, if any, of filter particles on smokers.
"Nor has Philip Morris hidden the issue from scientists. For example, in 2000, Philip Morris USA provided information on the health effects of filter fibres on smokers to the United States Institute of Medicine.
"Based on our assessment of the available data we believe that the filters we use do not pose additional health risks to smokers."