The Rebel Whopper divided opinion within the vegan community when it was launched in January, as it features mayonnaise (which can be removed), but is cooked alongside beef, which means cross-contamination is extremely likely.
According to the Advertising Standards Authority (ASA), the advert's claim that the burger is '100% Whopper, no beef', could be interpreted to mean the burger is free from animal products and is suitable for vegans and vegetarians.
The ASA received 10 complaints about the ads, with people alleging the sandwich is not suitable for vegetarians, vegans, or people with egg allergies - but this is not clear in the marketing.
According to the ASA: "The green color palette and the timing of the ad and product release to coincide with 'Veganuary' contributed further to the impression that the product was suitable for vegans and vegetarians.
While some of the ads included a small disclaimer saying the patty is cooked next to meat, the ASA said it is 'not sufficiently prominent to override the overall impression that the burger was suitable for vegetarians and vegans'.
It added: "We concluded that the ads were misleading. The ads must not appear again in their current form."
Burger King argued that it had been clear that the product is not vegan or vegetarian-friendly, saying: "We communicated from the outset that the Rebel Whopper is aimed at a flexitarian audience."
The fast-food giant added that the disclaimer on the ad implied the sandwich was may not be suitable for vegetarians and vegans, and that this was 'clearly communicated' to journalists and on social media.
The chain added that a 'Vegetarian Butcher' logo (the name of the company that makes the burger's patty) was left off TV ads, as it was considered 'potentially misleading'.
Despite Burger King's claims that it was clear on social media that the burger was aimed at flexitarians, it shared an Instagram post in January describing the Rebel Whopper as 'our first plant-based burger'.
When Plant Based News contacted Burger King asking about cross-contamination, a spokesperson for the chain said: "Whilst the patty itself is completely plant-based, the Rebel Whopper is cooked on the same Burger King broiler as our beef to provide our signature flame-grilled taste, so we do not label the burger as vegan or vegetarian. Also, like the classic Whopper, the Rebel Whopper does include mayonnaise so is not suitable for vegans – however, customers can, of course, ask for theirs without mayo to have it their way.
"The burger patty is plant-based made from soy, but as you said as standard the Rebel is served with mayo which, again, has always been made clear in advertising and in the press release and the fact that the mayo has egg is very explicit in allergen information in-store and online. The labeling of the burger meets guidelines and again, has always been very consistent and clear on our side. "
When PBN pointed out that the Instagram caption describes the burger as 'plant-based', we received no further replies.