By Brady Dennis, Apr. 24, 2014, Bostonglobe.com

WASHINGTON — The Food and Drug Administration will for the first time regulate the booming market of electronic cigarettes, as well as cigars, pipe tobacco, and hookahs, under a proposal to be released Thursday.

The move would begin to place restrictions on the nearly $2 billion a year e-cigarette industry, which for years has operated outside the reach of federal regulators. If adopted, the government’s plan would force manufacturers to put restrictions on sales to minors, stop handing out free samples, place health warning labels on their products, and disclose the ingredients. E-cigarette makers also would be banned from making health-related claims without scientific evidence.

The FDA’s proposal stops short of broader restrictions sought by manytobacco-control advocates. Regulators at this point are not seeking to halt online sales of e-cigarettes, curb television advertising, or ban the use of flavorings such as watermelon, grape soda, and pina colada — all tactics that critics say are aimed at attracting young smokers and which have been banned for traditional cigarettes.

Those restrictions may come eventually, FDA officials said, but not before more rigorous research can establish a scientific basis for tougher rules.

‘‘Right now, for something like e-cigarettes, there are far more questions than answers,’’ said Mitch Zeller, director of the FDA’s Center for Tobacco Products.

Thursday’s action is about expanding the FDA’s authority to products that have been ‘‘rapidly evolving with no regulation whatsoever,’’ in order to create a foundation for broader regulation in the future, he said. ‘‘It creates the framework. We’re calling this the first step. . . . For the first time, there will be a science-based, independent regulatory agency playing a vital gate-keeping function.’’

Zeller and FDA Commissioner Margaret Hamburg discussed outlines of the proposal with reporters Wednesday under an agreement that no details would be published until Thursday morning.

E-cigarettes vary from brand to brand, but they generally resemble the size and shape of traditional cigarettes. Instead of burning tobacco, the battery-powered devices heat up flavored, nicotine-laced liquid, turning it into a vapor that the user inhales. Supporters argue that makes e-cigarettes an attractive alternative to their cancer-causing tobacco counterparts.