This is a major step forward in stopping the tobacco industry from promoting its new addictive products to children and teenagers.
British American Tobacco (BAT) and three other e-cigarette firms have been banned from promoting their products on public Instagram pages in a ruling described by health campaigners as "a huge step forward".
UK regulations prohibit online advertising of e-cigarettes but BAT, Ama Vape Lab, Attitude Vapes and Mylo Vapes all argued that their Instagram posts simply provided permitted factual information such as the name, content and price of their products.
The Advertising Standards Authority (ASA) disagreed, ruling that the posts "clearly went beyond the provision of factual information" and were promotional in nature.
The ruling followed complaints from Action on Smoking and Health, Campaign for Tobacco-Free Kids and Stop (Stopping Tobacco Organiaations and Products) that the posts broke advertising rules by promoting unlicensed, nicotine-containing e-cigarettes and their components on Instagram.
The complaints focused on Instagram posts including seven early this year by BAT for its e-cigarette brand Vype, three of which featured captioned pictures of singer Lily Allen.
Other posts promoting Vype congratulated Rami Malek on his Bafta best actor award for Bohemian Rhapsody and featured a picture of model Olivia Jade Attwood smoking an e-cigarette.
BAT said it used Instagram to communicate factual information about Vype that adult vapers and smokers might not be aware of, nor able to find on its e-commerce website, adding that the images "ensure that there was a genuine and logical connection to the product".
A post by Mylo Vape in October included a picture of a woman with an e-cigarette and the caption "#repost @rae_eleanor loving her #mylo", while Attitude Vapes posted a black and white image of someone smoking an e-cigarette with the caption "Attitude is everything #LiquidsWithAttitude".
Ama Vape's post in March included an image of someone smoking its Shock Spearmint product with the caption "SHOCK Spearmint! With @amiiegiffen."
The ASA said a social media page or account might fall within the rules if it could only be found by those actively seeking it.
However it noted it was possible for posts from a public Instagram account to be automatically distributed to users following the hashtags they contained or possible for the posts to appear on another user's Instagram Explore page, where content was automatically generated for the user to see.
The ASA said: "We considered both mechanisms were consistent with content being pushed to consumers without having opted into to receive the message it contained and therefore that neither mechanism was equivalent to actively seeking out information about e-cigarettes.
"Given those characteristics, we considered that material from a public Instagram account was not analogous to a retailer's own website and that material posted from such an account was therefore subject to the prohibition on advertising of unlicensed, nicotine-containing e-cigarettes, meaning that neither promotional nor factual content was permitted."
The ASA also found that, in any case, the ads contained content which "clearly went beyond the provision of factual information and was promotional in nature".
In the case of BAT, the posts contained "unrelated content about awards ceremonies or other events, and the imagery of Lily Allen, Olivia Jade Attwood and House of Holland branding were all significantly featured without being directly related to the product itself".
The ASA banned the ads, warning that they "should not be made from a public Instagram account in future, unless they had taken steps to ensure they would only be distributed to those following their account and would not be seen by other users".
Simon Cleverly, group head of corporate affairs at British American Tobacco, said: "In relation to the complaint that we were promoting unlicensed, nicotine-containing e-cigarettes and their components on Instagram, while we believed that the content included in the complaint was compliant with the ASA's CAP Code, we will abide by the ASA's decision and recommendation to remove the relevant posts and amend our Instagram account settings."
Professor Anna Gilmore, director of the Tobacco Control Research Group at the University of Bath, the research partner of Stop, said: "This is a major step forward in stopping the tobacco industry from promoting its new addictive products to children and teenagers.
"But given that cigarette sales are falling and tobacco companies are desperate to recruit young people into using these new products, ongoing vigilance is essential."
Deborah Arnott, chief executive of the charity Action on Smoking and Health, said: "The law has always been clear that any advertising of e-cigarettes online is not permitted. BAT's defence that all they were doing was providing 'information' on social media, not promoting their products, has been blown out of the water.
"The ASA ruling leaves no doubt that BAT's social media tactics for Vype were both irresponsible and unlawful and must never be repeated."
A Facebook spokesman, on behalf of Instagram, said: "We do not allow adverts that promote the sale or use of tobacco or electronic cigarettes.
"Earlier this year we updated our policy to restrict organic content that depicts the sale or purchase of tobacco products to over-18s. We are currently updating our branded content policies to no longer allow paid promotions of these products too."
Josie Clarke is the PA consumer correspondent.