The boss of e-cigarette giant Juul has apologised to parents amid worries of an epidemic of vaping among children.
"I'd tell [parents] I'm sorry their child's using the product. It's not intended for them," Kevin Burns said.
The apology, made in a US television documentary being aired on Monday, was dismissed as fake and deceptive by an anti-smoking group.
Juul, which has begun a marketing push in the UK, is trying to cut teenage use, but faces lawsuits from parents.
"I hope there was nothing that we did that made it appealing to [children]," he says in the CNBC documentary: Vaporized: America's E-cigarette Addiction.
"As a parent of a 16-year-old, I'm sorry for them, and I have empathy for them, in terms of what the challenges they're going through."
Last month San Francisco became the first US city to ban vaping, making it illegal for shops to sell the product and online firms to send it to addresses there.
Mr Burns admitted that there still needs to be research into the long-term impact of vaping. "Frankly, we don't know today. We have not done the long-term, longitudinal clinical testing that we need to do," he said.
Last year, the US surgeon general Jerome Adams called vaping among US teenagers "an epidemic". The Food and Drug Administration found that 21% of school students vaped in 2018.
Stanford University paediatrics professor Bonnie Halpern-Felsher told CNBC that children are at risk of addiction to Juul products because they contain high levels of nicotine.
UK marketing drive
A young user told the documentary that, when she was 15, her Juul device was always with her. "I would always just, like, hit it because it was just so easy."
The company has tried to tackle use by children, including withdrawing from sale its popular sweet and fruit flavours.
Juul has also shut its Facebook and Instagram account after being accused by critics of marketing to young people. The company's early adverts featured bright colours and young models.
In just four years since it started, Juul has grabbed 40% of the US vaping market. Last year Marlboro-maker Altria paid $13bn for a 35% stake in the company.
In a statement to the BBC, the Campaign for Tobacco-Free Kids' president Matthew L Myers said the Juul apology was "following the tobacco playbook".
"Proclaim loudly that they don't want kids to use their product, while never admitting that their marketing targeted and attracted kids... There can be no doubt Juul's role in the current youth epidemic."
This month, Juul began a 12-week marketing campaign in the UK to encourage tobacco smokers to make the switch to vaping. The campaign features adult smokers, and billboard advertising will be at least 200 metres from schools.
Mr Burns told the documentary that Juul has had a "significant impact" on driving down traditional tobacco use in the US.