NEW YORK — Juul Labs Inc.’s legal woes expanded on Tuesday as 39 state attorneys general announced a joint investigation into whether the top U.S. e-cigarette maker is marketing its addictive nicotine products to children.

The probe will also examine Juul’s claims about its products’ nicotine content and their effectiveness in helping longtime smokers quit, the states said in a joint statement. The bipartisan effort is being led by Connecticut, Florida, Nevada, Oregon and Texas.

A similar coalition of states announced an investigation of opioid marketing in 2017. Many of those states — along with thousands of local and municipal governments — went on to file lawsuits against major opioid manufacturers and distributors, who are expected to pay tens of billions of dollars to settle claims.

Juul has been under fire following a surge in teen vaping and a lung-injury outbreak that sickened thousands and was later tied to THC-containing e-cigarettes.

“As Florida’s attorney general and a mother, I cannot sit on the sidelines while this public health epidemic grows, and our next generation becomes addicted to nicotine,” Republican Ashley Moody said in the statement.

Juul seeks to “earn the trust of society by working cooperatively with attorneys general, regulators, public health officials and other stakeholders to combat underage use and transition adult smokers from combustible cigarettes,” Juul spokesman Austin Finan said in a statement. “Our customer base is the world’s 1 billion adult smokers and we do not intend to attract underage users.”

Finan added that Juul in November stopped sales of flavored pods — other than tobacco and menthol — and halted the company’s television, print and digital advertising.

Juul was sued separately in November by California Attorney General Xavier Becerra and his New York counterpart, Letitia James, who both accused the company of trampling state marketing laws by targeting teenagers in advertisements, among other things.

At the time, New York cited a recent National Youth Tobacco Survey showing that about 4.1 million high school students and 1.2 million middle schoolers use e-cigarettes in the U.S. As of November, the Centers for Disease Control and Prevention reported 42 deaths tied to e-cigarettes or vaping, with a further 2,172 cases of associated lung injury reported nationwide.

The investigation comes at a critical time for Juul, which has been bulking up its science staff to try to win Food and Drug Administration clearance for its product, a step that could determine the future of the company.

Connecticut Attorney General William Tong said in the statement, “I will not prejudge where this investigation will lead, but we will follow every fact and are prepared to take strong action in conjunction with states across the nation to protect public health.”