UPDATE 1-U.S. seeks e-cigarette companies' data on advertising, sales

(Adds detail on FTC request, background on issue)

WASHINGTON, Oct 3 (Reuters) - The U.S. Federal Trade Commission has ordered a half-dozen e-cigarette companies to turn over sales and advertising data, the federal regulator said on Thursday, in the first sign of a likely probe into marketing practices by the companies.

The order was sent to JUUL Labs Inc, RJ Reynolds Vapor Company, Fontem US Inc, Logic Technology Development LLC , Nu Mark LLC and NJOY LLC, the FTC said in a statement.

The FTC is seeking annual sales data and information on giveaways, data on product placement and flavors, as well as information on the companies' use of celebrities as internet influencers and marketing on college campuses to sell the electronic smoking devices.

Part of the FTC mission is to enforce truth-in-advertising laws.

"The goal is to assist the Commission, policy makers, and the public to better understand the rapidly growing e-cigarette market," the FTC said.

The FTC request comes amid a mysterious outbreak of serious vaping-related lung illnesses whose cause has yet to be determined.

The U.S. Centers for Disease Control and Prevention has said that there have been 805 confirmed and probable cases of lung illness in 46 states, as well as 12 deaths associated with vaping in the United States. Four other U.S. deaths have since been reported by states. The CDC is expected to update its numbers later on Thursday.

Meanwhile, the agency has urged people to stop using e-cigarette or vaping products, including those containing THC, the psychoactive ingredient in marijuana.

The Trump administration has announced plans to remove all flavored e-cigarette products from the market in the United States amid concerns that flavors like mint and mango attract children to the products. (Reporting by Susan Heavey, Diane Bartz and Bryan Pietsch Editing by Chizu Nomiyama and Bill Berkrot)