James Monsees, co-founder and chief product officer at JUUL Labs Inc., appears before the House Economic and Consumer Policy Subcommittee which is examining JUUL's role in the youth nicotine epidemic, on July 25, 2019 in Washington, DC.

Federal health officials slammed vaping company Juul on Monday for illegally advertising its nicotine pods as a safer alternative to cigarettes, threatening to fine or even seize the company's products if it doesn't correct its marketing.

The Food and Drug Administration sent a warning letter to CEO Kevin Burns after reviewing testimony from two days of hearings on Juul in the U.S. House in July. FDA investigators found the company broke the law "by selling or distributing them as modified risk tobacco products without an FDA order in effect that permits such sale or distribution."

"Regardless of where products like e-cigarettes fall on the continuum of tobacco product risk, the law is clear that, before marketing tobacco products for reduced risk, companies must demonstrate with scientific evidence that their specific product does in fact pose less risk or is less harmful," Acting FDA Commissioner Ned Sharpless said in a statement.

"JUUL has ignored the law, and very concerningly, has made some of these statements in school to our nation's youth," Sharpless said.

FDA rules require a company to receive regulatory approval before marketing any tobacco product as less harmful than cigarettes. Juul's vaping devices have never been submitted to the FDA for review. The company has 15 days to respond to the agency.

In a separate letter sent Monday, the FDA additionally requested more information about the company's marketing practices. Specifically, the agency is looking for any scientific evidence or data that shows whether its use of words like "switch" and "alternative" give people the idea that Juul's e-cigarettes are less harmful than combustible cigarettes.

The FDA also said it was investigating whether the company withheld materials from the agency that were otherwise provided to Congress. The agency asked Juul to turn over everything it sent to the Hill in its separate investigation.

Juul spokesman Ted Kwong said the company was "reviewing the letters and will fully cooperate."

The FDA is "troubled" about Juul's marketing and outreach efforts, particularly in high schools, Sharpless said. He pointed to testimony from a student who said that a Juul representative came into his school touting it as "much safer than cigarettes" and that the "FDA was about to come out and say it was 99% safer than cigarettes."