FDA warns stores to stop selling Elf Bar, the top disposable e-cigarette in the U.S.

The U.S. Food and Drug Administration campus in Silver Spring, Md., is photographed on Oct. 14, 2015. (Andrew Harnik/AP)

WASHINGTON — The Food and Drug Administration on Thursday said it has sent warning letters to dozens of retailers selling fruit- and candy-flavored disposable e-cigarettes, including the current best-selling brand, Elf Bar.

It's the latest attempt by regulators to crack down on illegal disposable vapes that have poured into U.S. stores in recent years.