Online dating service eHarmony has been accused of promoting "fake news" after it was banned from claiming it used a "scientifically proven matching system".
The advertising watchdog ruled that a billboard advert for the website was "misleading" because eHarmony had failed to prove it offered singletons a "significantly greater chance of finding lasting love".
The advert, which was displayed on a London Underground platform in July, said: "Step aside, fate. It's time science had a go at love."
It added that "eHarmony's scientifically proven matching system decodes the mystery of compatibility and chemistry so you don't have to".
Lord Lipsey, who lodged the complaint that triggered the ruling, said: "Phrases like 'scientifically proven' should be confined to claims that are just that, not used in crude puffery designed to lure in those longing for love.
"This is a new form of fake news which the ASA has rightly slapped down."
eHarmony said it used an algorithm based on scientific theories from literature on assortative mating, where users were required to complete lengthy questionnaires to determine their personality traits, values and interests.
Users were then matched to other individuals whose responses complemented their own preferences, as well as matching a specific percentage of a list of personality factors that eHarmony determined.
The algorithm was based on data collected from more than 50,000 married couples in 23 countries, eHarmony said.
The website provided a copy of two published studies to the Advertising Standards Authority (ASA) which it claimed reported higher levels of marital satisfaction for couples who met through eHarmony than any other sources.
But the ASA said consumers would interpret the claim "scientifically proven matching system" to mean that scientific studies had found that the website offered users a significantly greater chance of finding lasting love than what could be achieved if they did not use the service.
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The watchdog noted that neither of the two studies provided by eHarmony revealed anything about the overall percentage of its users who had found lasting love after using the website compared to other sources.
The ASA said: "Because the evidence provided by eHarmony did not demonstrate that their matching system offered users a significantly greater chance of finding lasting love than what could be achieved if they didn't use the service, we concluded that the claim 'scientifically proven matching system' was misleading."