U.S.-focused tobacco stocks tumbled Monday following a Wall Street Journal report that suggested the Food & Drug Administration is prepared to ban the sale of menthol cigarettes alongside a crackdown on teenage vaping.

FDA Commissioner Scott Gottlieb is set to close a loophole that has kept menthol cigarettes on the market for decades, the Journal reported, citing senior agency sources. The FDA concluded in a 2013 report that menthol cigarettes are more difficult for users to quit and thus pose a more significant health risk than traditionally-flavored brands. The Journal story followed similar reports last week that its also planning a ban on the sale of candy-flavored e-cigarettes.

"It must be emphasised that at this stage these reports are still rumours and they make it clear that it would take some time to draw up the ban and then implement it," said Ian Forrest, investment research analyst at The Share Centre. "However, they follow the news in October that the FDA is planning to crack down on the growing use of e-cigarettes by young people."

British American Tobacco  , which gets around a quarter of it revenues from menthol-flavored sales through its 2015 acquisition of Newport, saw its shares marked 9% lower in London trading Monday, a move that burnt more than $10 billion in market value. Rival Imperial Brands plc (IMBBY) , which is estimated to earn around 11% from menthol sales, and also markets 'blu'-branded e-cigarettes in the United States, slumped 3.5% to £26.53 per share.

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Last week, Altria Group (MO) - Get Report shares fell nearly 3% on the final day of trading following a series of reports that suggested the FDA was ready to move on banning the sale of candy-flavored e-cigarettes at gas stations and convenience stores. 

"E-cigs have become an almost ubiquitous ‒- and dangerous ‒- trend among teens," Gottlieb said in September. "The disturbing and accelerating trajectory of use we're seeing in youth, and the resulting path to addiction, must end. It's simply not tolerable."

Altria CEO Howard A. Willard III told the FDA last month that his company was prepared to withdraw the same of some e-cigarette products, admitting that while he considered them an important alternative to adults looking to quit, the "current situation with youth use of e-vapor products, left unchecked, has the potential to undermine that opportunity."