Juul Labs, the vaping company that has long insisted it never marketed its products to teenagers, purchased ad space in its early days on numerous youth-focused websites, including those of Nickelodeon, the Cartoon Network, Seventeen magazine and educational sites for middle school and high school students, according to a lawsuit filed Wednesday in Massachusetts.

The suit, brought against Juul by the state's attorney general, Maura Healey, presents some of the starkest evidence to date that the company was targeting young nonsmokers during its launch period, from June 2015 through early 2016.

Juul executives declined immediate comment on the lawsuit.

According to the suit, Juul rejected an initial marketing proposal by a publicity firm it had hired, Cult Collective, that would have branded it as a technology company with a target audience of adult smokers. The proposal that was rejected featured images of outdated technology like clunky telephones and joysticks, with a picture of a Juul device and the words, "Smoking Evolved."

Instead, the lawsuit said, Juul dropped the Cult Collective and hired an in-house interim art director to produce "Vaporized," the youth-oriented campaign, featuring beautiful models in provocative poses.

"Juul decided against doing an ad campaign designed for an older audience and instead specifically chose one that targeted young people," Healey said. "The information that we uncovered in our investigation demonstrates Juul's intent — they didn't accidentally create an advertising campaign with young and attractive people. That's what they were going for all along."

The 66-page complaint includes images of young models that it claims were displayed in digital ads on websites, mobile apps and social media. It includes an extensive list of sites where Juul products were promoted that the lawsuit says were clearly aimed at teenagers and even younger children.

The suit said Juul paid a company to place digital promotions across websites.

The list of sites where they ran includes educational brands like basic-mathematics.com, coolmath.com, math-aids.com, mathplayground.com, mathway.com, onlinemathlearning.com, purplemath.com and socialstudiesforkids.com.

It includes sites targeted to young girls such as such as dailydressupgames.com, didigames.com, forhergames.com, games2girls.com, girlgames.com, and girlsgogames.com.

It also includes sites geared to high school students looking at colleges, like collegeconfidential.com, and sites aimed at much younger children, including allfreekidscrafts.com, hellokids.com and kidsgameheroes.com.

The lawsuit charges that Juul attempted to recruit celebrities and social media influencers with large numbers of underage followers, such as Miley Cyrus, Cara Delevingne and Kristen Stewart, and social media influencers Luka Sabbat and Tavi Gevinson.

"Juul allowed more than 1,200 accounts to be established for Massachusetts consumers using school e-mail addresses, including e-mail addresses associated with high schools in Beverly, Malden and Braintree and shipped its products to recipients with obviously fabricated names, like 'PodGod,' " the lawsuit states.

The complaint also contained an e-mail sent from a Juul customer-service address advising a young customer how to get around age restrictions. In the e-mail from support@juulvapor.com dated Feb. 21, 2018, the complaint said, "Don from the 'Juul Care Team' told a consumer whose order had been canceled due to an age verification failure: 'The legal age to purchase nicotine products in Milton, Mass. is 21 years old and above. If you have friends or relatives in Quincy, Mass., you may use their address as a shipping address for your order.' "

The lawsuit claims that Juul worked with hundreds of Massachusetts stores to sell its products, including approximately 850 outlets that the company knew were cited by the Food and Drug Administration (FDA) for attempting to sell tobacco products to underage teenagers. Although Juul caught some of these stores trying to sell its devices and pods to youths, the lawsuit said, it continued to work with those stores.

The lawsuit comes at a time when Juul is struggling to improve its reputation. K.C. Crosthwaite, who replaced Kevin Burns as chief executive in September, stopped sales of most flavored e-cigarettes ahead of the recent FDA flavor ban.

Juul, like other e-cigarette companies, has until May to apply for FDA approval to stay on the market. The FDA will consider several factors, among them whether Juul can keep its products out of the hands of minors.

Earlier this week, the state of Pennsylvania sued Juul, alleging that the company misled consumers about the addictive nature of its liquid nicotine pods and marketed them to young people. Josh Shapiro, the state's attorney general, asked the court to ban Juul — or, barring that, ban all non-tobacco-flavored Juul products.

Arizona, California, Illinois, Minnesota, Mississippi, New York and North Carolina are among the other states that have sued Juul over its marketing practices, as well as the District of Columbia.