By Chris Kirkham and Manas Mishra

(Reuters) – The U.S. Food and Drug Administration (FDA) on Wednesday released formal plans to curb the sale of flavored e-cigarettes and slow a surge in teenage use of the popular nicotine devices.

FDA Commissioner Scott Gottlieb, who has called teenage use an “epidemic,” issued the draft guidelines during his final weeks as head of the agency, after a surprise resignation announcement last week.

The proposal would allow traditional retailers such as convenience stores to sell tobacco, mint and menthol e-cigarettes, which the FDA says are more popular among adults than minors. But other flavors could only be sold in stores or online when strong age-verification protocols are in place.

In an interview on Wednesday, Gottlieb said the new guidelines give the agency flexibility to further restrict sales if youth use trends continue.

The agency is paying close attention to “pod-based” e-cigarettes such as the ones popularized by Juul Labs Inc, he said. Those devices use pre-filled, flavored nicotine cartridges and have been especially popular among U.S. high school students.

“The FDA did this in a fashion that’s going to allow us to put in place additional restrictions if the youth rates continue to grow,” Gottlieb said. “It allows us to very quickly adjust our policy further.”

Under the proposal, makers of e-cigarette products would have to submit a formal application to the FDA by August 2021 in order to keep selling them, a year earlier than previously proposed.

Shares of tobacco companies Altria Group Inc and Philip Morris International Inc, which have been pressured by recent news of rising regulatory scrutiny into e-cigarettes, initially fell on the news before edging higher.

Gottlieb had said in November that the agency planned more restrictions on flavored e-cigarettes.

Juul and Altria, which took a 35 percent stake in Juul last December, said on Wednesday they supported the FDA’s efforts to combat underage use. Juul announced its own plans in November for stricter age-verification requirements online and in retail stores.

Public health and anti-smoking groups said the agency’s plan falls short of what is needed to curb underage e-cigarette use.

“A public health crisis of this magnitude demands faster and more forceful action than the steps announced by the FDA,” Matthew Myers, president of the Campaign for Tobacco-Free Kids, said in a statement.

Data released in November by the FDA and the U.S. Centers for Disease Control and Prevention showed a 78 percent increase in high school students who reported using e-cigarettes in the last 30 days, compared with the prior year.

The draft guidelines are expected to be finalized within the next three months, following a public comment period.

(Reporting by Chris Kirkham in Los Angeles and Manas Mishra in Bengaluru; Editing by James Emmanuel and Richard Chang)