Banning flavoured vaping products in the UK would drive people back to smoking, Public Health England (PHE) has said.
Responding to US President Donald Trump's plan to axe flavourings due to concerns about youths taking up e-cigarettes, PHE said the flavours helped smokers switch from more dangerous tobacco.
PHE has come under fire from some academics over its stance on e-cigarettes, with some saying it wilfully ignores evidence that vaping is harmful.
Martin Dockrell, head of tobacco control at PHE, said it plans to publish a comprehensive evidence review on the safety of e-cigarettes early next year.
In a statement he said: "E-cigarette flavours are an important advantage that vapes have over smoking and play an important part in encouraging smokers to switch.
"Similar choice of flavours exist in the US and UK and yet we do not have the same levels of youth vaping here.
"Our much lower rates are due to our much stricter advertising regulations and possibly our lower nicotine cap.
"Banning flavours would just likely provoke vapers to relapse back to smoking, leading to more adult smoking role models for young people, which we know is the key driver in young people starting to smoke."
Data published by PHE in February shows the number of children and young people trying vaping is on the rise.
While overall use of e-cigarettes among young people remains low, the number who have ever tried it has almost doubled in four years.
The report, led by researchers at King's College London, looked at surveys relating to e-cigarette use among young people, the most recent of which was the Action on Smoking and Health YouGov survey of more than 2,000 children aged 11 to 18 in 2018.
The survey showed that 11.7% of 11 to 18-year-olds in 2018 had tried e-cigarettes once or twice at some point, almost double the 6.5% in 2014.
The proportion trying vaping before a tobacco cigarette rose from 8% in 2014 to 21% in 2018.
Meanwhile, the US president has said vaping has become such a problem that he wants parents to become more aware.
The Food and Drug Administration (FDA) will develop guidelines to remove from the market all e-cigarette flavours except tobacco.
It comes after a sixth person died from a serious respiratory illness linked to vaping