LONDON (Reuters) - Health campaigners have written to U.S. regulators accusing Philip Morris International ( PM ) of misrepresenting past regulatory decisions, seeking to disrupt the launch of its flagship heated tobacco device IQOS in the United States.

The world's biggest tobacco company by market value has spent billions of dollars developing the product, which investors see as key to driving future growth. But it needs permission from the U.S. Food and Drug Administration to sell it in the world's second largest tobacco market by revenue.

Six anti-tobacco and health groups, including the Campaign for Tobacco-Free Kids, the American Academy of Pediatrics and the American Lung Association, wrote to the FDA to oppose IQOS-related applications PMI has submitted to the agency.

"PMI has repeatedly made misleading and deceptive statements wrongly suggesting that the FDA has found that IQOS reduces the risk of disease," the letter, dated June 27 and reviewed by Reuters, said.

The campaign groups allege that PMI violated the FDA's orders by suggesting IQOS offered lower risks than cigarettes. Their letter cited four examples of such statements in the United States, the Philippines, Mexico and Kazakhstan.

They also said in the letter that upcoming independent studies contradict PMI's findings about how many IQOS users completely switch to the device from cigarettes.

Presentations on the studies from the International Tobacco Control Project (ITC) at Canada's University of Waterloo are attached to the letter as exhibits.

They show the ITC found a far lower rate of IQOS users had quit smoking in Japan and Korea than estimates from PMI.

These factors "directly bear on whether PMI should be permitted to market IQOS" in the United States, the campaigners' letter said.

The contents of the letter have not been previously reported.

Asked by Reuters to respond to the letter, a PMI spokesperson said the company was proud to discuss the FDA's conclusions on IQOS.

The spokesperson did not address each example but said some of the language flagged by campaigners was, in the company's view, compatible with the FDA's orders.

"Wherever we discuss our science and our products, we do so in accordance with all applicable laws," the spokesperson said.

Reuters could not determine whether the campaigners' letter would change the FDA's approach to IQOS. The agency said it had received the letter and would respond directly to the senders. It did not comment further.

Devices like IQOS heat up sticks of ground tobacco without burning them in an attempt to avoid the harmful chemicals released via combustion.

The FDA first authorised PMI to sell an older version of IQOS in 2019. It subsequently authorised the company to market it as offering reduced exposure to harmful chemicals versus cigarettes for smokers who completely switch - known as an "exposure modification order".

The FDA can also issue a "risk modification order", authorising a company to claim its product reduces the risk of tobacco-related harm and disease. But this is harder to prove, especially without long-term, epidemiological studies.

The FDA rejected PMI's previous application to say its older IQOS device results in reduced health risks, saying there wasn't sufficient evidence to support this.

PMI applied in 2023 to renew its existing exposure modification orders. Later that year, it also applied to sell and market a newer version of the IQOS device in the same way. The FDA has yet to decide on these applications.

Marketing the product as having health benefits compared to traditional cigarettes could help PMI persuade consumers to switch as well as afford it tax benefits versus cigarettes in some U.S. states.

SWITCH RATES

The campaign groups also cited preliminary data from ITC studies in Japan and Korea, saying it contradicted PMI's findings about how many IQOS users completely switch from cigarettes.

The studies have been presented at academic conferences but have not yet been submitted for publication in a journal, ITC researchers told Reuters. As a result, study abstracts have been peer reviewed but the full findings have yet to go through that process.

Japan is IQOS' largest market and the introduction of heated tobacco there coincided with an accelerated decline in cigarette sales.

PMI estimates more than seven out of 10 of its registered IQOS customers globally have quit cigarettes. A 2023 PMI application to the FDA emphasised that the majority of IQOS users were using IQOS exclusively.

However, the ITC's researchers put the percentage of all IQOS users that had quit smoking at just 15% in Japan and 30% in Korea in 2021.

Users most commonly used IQOS and cigarettes simultaneously, known as "dual use", often leading to an overall increase in tobacco consumption, the ITC researchers found.

PMI pointed to a 2019 Japanese government health survey, where 75% of respondents who reported using heated tobacco said they did not smoke.

However, a paper published this year, led by researchers from Georgetown University, highlighted flaws in the government's survey, including changes to the question format that can lead to under-reporting of smoking.

Other surveys have also found higher rates of dual use than the government, it said.

(Reporting by Emma Rumney; Editing by Matt Scuffham and Emelia Sithole-Matarise)