WASHINGTON — Federal health regulators and law enforcement officials on Monday vowed to work more closely to stop sales of illegal electronic cigarettes, which have grown into a multibillion-dollar business in the U.S. while skirting government oversight.

The Food and Drug Administration said it would launch a new task force on this issue with the Department of Justice and several other agencies, including the U.S. Postal Service.

The FDA has authorized a handful of e-cigarettes for adult smokers looking for alternatives to traditional cigarettes. The agency has rejected applications for millions of other proposed products.

But thousands of unauthorized vaping products continue to flow into the U.S., largely from China. They include major disposable vape brands like Elf Bar, which was the most popular e-cigarette among underage teens last year, according to federal data.

The FDA and Justice Department announcement comes two days before a Senate hearing scrutinizing the lack of government enforcement action against makers and sellers of unauthorized e-cigarettes.

The multi-agency task force was proposed by outside experts in 2022 as part of a blistering critique of the FDA's tobacco program.

The experts channeled longstanding grievances from groups on opposing sides of the vaping issue. Public health groups want the FDA to more aggressively police illegal flavored e-cigarettes that appeal to teenagers. Tobacco companies complain that the FDA is unwilling to approve newer e-cigarettes that might help adults quit smoking.

The FDA has sent hundreds of warning letters to vape shops and e-cigarette manufacturers in recent years, calling on them to remove or discontinue their products. But the letters are sometimes ignored. And FDA officials have increasingly noted that they rely on the Justice Department to bring lawsuits against bad actors.

Only last year did the FDA announce the first fines against vaping companies for selling unauthorized e-cigarettes.