WASHINGTON, Sept. 12 (Xinhua) -- The United States Food and Drug Administration (FDA) announced on Wednesday a plan to clamp down on flavored e-cigarettes on the U.S. market.

It came after the agency issued over 1,300 warning letters and civil money penalty fines to retailers who illegally sold some e-cigarette products to minors this summer.

The e-cigarette use among the youth has hit "epidemic proportions," according to the FDA, arguing flavored e-cigarettes appeal to teenagers.

"We see clear signs that youth use of electronic cigarettes has reached an epidemic proportion, and we must adjust certain aspects of our comprehensive strategy to stem this clear and present danger," said FDA Commissioner Scott Gottlieb.

Gottlieb said the FDA had started to "crack down on retail sales of e-cigarettes to minors."

In 2017, more than 2 million middle and high school students were current users of e-cigarettes, according to the agency.

The vast majority of the violations were for the illegal sale of five e-cigarette products: Vuse, Blu, JUUL, MarkTen XL, and Logic, which currently comprise over 97 percent of the U.S. market for e-cigarettes, according to the FDA.