Several ads for the online GP consultation service Push Doctor have been banned for implying that it was provided by the NHS and therefore free of charge.
A poster displayed on London Underground trains in August last year said: "The UK's most popular online doctor service is open 6am-11pm, 7 days a week, allowing you to access an NHS GP whenever you want."
A link in the header bar of the Push Doctor website, labelled "NHS", linked to a page headed "NHS & PUSH DOCTOR".
It said: "Speak with an NHS trained doctor in as little as 6 minutes," while a paid-for Google ad said the service was "Proud To Be An NHS Commissioned Technology Provider".
The Advertising Standards Authority (ASA) received 31 complaints that the ads were not clear that there were charges for the service and implied that it was provided by the NHS.
Push Doctor said consumers were already sufficiently aware of the brand and would know that it was a paid-for, non-NHS service, confirming that a 10-minute consultation cost £20, referrals to specialists cost £15 and prescriptions incurred an £8 administration fee.
However the ASA said most consumers who saw the poster were unlikely to be familiar with Push Doctor, its position as a private healthcare provider or its links with the NHS.
It said: "We considered that the poster misleadingly implied the advertised service was provided by the NHS and, as a result, that it was misleading because it did not make clear a cost was associated with the service.
"Because we considered consumers were likely to understand from the website home page that the service offered was an NHS service and subsequently provided free of charge, consumers were likely to start the booking process under that impression."
It also concluded that the Google ad misleadingly implied the advertised service was provided by the NHS.
The ASA noted that Push Doctor encouraged customers to post Trustpilot reviews but omitted those that had fewer than four stars from its website without making this clear to customers.
It ruled that the three ads must not appear again, adding: "We told Push Doctor to ensure their ads did not imply that they provided an NHS service or that their service was free of cost.
"We told them that if they were selective about which reviews to reproduce on their website, they should ensure it was clear to consumers that it was not organic content reflective of all recent reviews."
Eren Ozagir, founder and chief executive of Push Doctor, said: "This finding relates to a small campaign run only in London for two weeks over eight months ago. We took the decision, before any notification from the ASA, not to run the adverts beyond the two-week trial and the few points that were upheld here have long since been voluntarily addressed.
"As the market leader we continuously test a range of communications to help customers understand the changes happening in a previously very traditional sector and to ensure patients are able to make informed choices about the options available to them today."