WASHINGTON, D.C. — 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 restrict 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 many tobacco-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 might 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 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.

Congress passed a law in 2009 giving the FDA broad power to regulate cigarettes, including requirements for new warning labels, restrictions on ads and explicit approval of new products. The law also gave the FDA authority to broaden its jurisdiction over other tobacco-related products. While the agency has long indicated that it planned to do just that, action as been slow in coming.

“In the absence of any meaningful regulation, the e-cigarette manufacturers have acted as if it’s the wild, wild West, with no rules and no restraints,” said Matthew Myers, president of the Campaign for Tobacco-Free Kids, who had not seen the particulars of the FDA proposal. “Their advertising is exactly the same type of advertising that made cigarettes so appealing to young people” decades ago.

Whatever changes are coming won’t happen overnight. The public will have 75 days to comment on the proposal. After the FDA sorts through a likely tidal wave of responses and finalizes its regulations, companies will have to begin complying almost immediately with the proposed age and identification restrictions. But they will have two years to submit applications to the FDA to approve their products, which can remain on the market in the meantime.

The FDA’s effort to begin overseeing the sprawling e-cigarette market comes at a critical time. Sales have doubled year after year, with no signs of slowing, according to some industry analysts. That pales in comparison to the estimated $80 billion-a-year U.S. market for conventional tobacco products, but the gap is shrinking steadily. In addition, tobacco giants such as Lorillard, Reynolds and Altria have entered the e-cigarette market in recent years, joining hundreds of smaller manufacturers.

The move toward federal regulation also comes amid an impassioned debate over simple questions that so far have no simple answer: Will e-cigarettes eventually cause more people or fewer to smoke? Will the devices emerge as a healthier alternative that make cigarettes obsolete, or will they act as a gateway to smoking and undermine a half-century of efforts to reduce tobacco-related deaths, which still kill an estimated 480,000 Americans annually?

“There’s such a huge debate over whether e-cigarettes are a good thing or a bad thing for public health,” said Kenneth Warner, a tobacco researcher and professor of public health at the University of Michigan. “But we’re in a kind of factual vacuum. There are not that many [reliable] studies. . . . We really don’t know the right answer.”

Warner, who had not seen the proposal, said the FDA will have to walk a fine line in the way it treats e-cigarettes. On one hand, the agency must set reasonable restrictions, such as keeping nicotine-delivery devices out of the hands of minors and creating safe manufacturing standards. On the other hand, if e-cigarettes do hold the potential to help some people quit smoking, the agency doesn’t want to stymie innovation and crush an industry that’s quickly evolving.

“It’s a tricky balance,” Warner said. “Even in an environment devoid of politics and lawsuits, it would be a challenge to come up with the right mix of regulations. . . . Figuring out how to do this is going to be hard, and it isn’t going to happen quickly.”

The cigar and e-cigarette industries have long been preparing for the inevitability of federal regulation — and working hard to try to shape it. For example, makers of “premium cigars” have been lobbying intensely to not be lumped in with the fruit-flavored, corner-store varieties that public health experts say target kids — a distinction FDA officials have said they are willing to consider.

E-cigarette executives have been every bit as aggressive, making their case over the past year in meetings with FDA regulators, members of Congress and state and local officials, seeking to avoid some of the stringent rules that govern conventional cigarettes. In essence, they have argued that e-cigarettes vapor is far less harmful than cigarette smoke, with its cancer-causing toxins, and can actually help smokers kick the habit. Therefore, the manufacturers say, they should be subject to kinder, gentler oversight — and lower taxes — than traditional cigarettes.

At the same time, manufacturers have been fighting growing regulation in cities and states. Numerous cities, from Los Angeles to Chicago to Boston, have banned e-cigarettes in public places, and dozens of state attorneys general have urged federal regulators to speed up restrictions on marketing the devices to young people.

The e-cigarette industry also has faced questions about the safety and accessibility of its products. The Centers for Disease Control and Prevention reported this month that calls to poison centers involving e-cigarettes have surgedin recent years as the products have gained in popularity, with most of the incidents involving children younger than 6 who have accidentally ingested the liquid nicotine.

Last year, the CDC reported a dramatic increase in the number of high school students who said they had tried e-cigarettes, including some who had never smoked. That fueled concerns among some public health officials that the devices could lead users toward traditional smoking. E-cigarette advocates argue there’s little evidence to support such a claim.

Greg Conley, a board member of the American Vaping Association, said the e-cigarette industry supports sensible federal regulations, such as restricting sales to minors, child-resistant packaging and standardized labeling. But Conley, who had not seen the details of the proposal, said he and others fear that the FDA will drive out of business small and medium manufacturers, as well as many bricks-and-mortar vape shops, if it regulates too overzealously in coming years.

“They could completely wipe out the growth in e-cigarettes. . . . They could destroy a big part of the industry and send a lot of it underground,” he said. “I’m cautiously pessimistic.”