The Advertising Standards Authority (ASA) has slammed holiday-reviews site TripAdvisor, claiming it's "misleading" web users.

KwikChex Ltd and two hotels made complaints over the site's claims that it offered "trusted advice from real travellers", "reviews you can trust" and "honest travel reviews and opinions from real travellers around the world" as TripAdvisor did not check the reviews and could not prove the comments were written by genuine real travellers.

The website said it did not claim to be 100 percent fraud-free and that no reviews site could guarantee that. However, it said it uses an "advanced and highly effective fraud detection systems" which included commenters signing a declaration that their review is genuine and honest, as well as offering establishment owners the chance to respond to reviews publicly on the site. Furthermore, it said there was no practical way to verify the reviewer's identities such as by credit card or reservation details.

However, the ASA has upheld the complaint saying the claims could in fact be misleading

"Because we considered that the claims implied that consumers could be assured that all review content on the TripAdvisor site was genuine, when we understood that might not be the case, we concluded that the claims were misleading," the ASA said.

The ASA has now ordered TripAdvisor to remove all claims and statement that imply its reviews are from real travellers and are honest, real or trusted.

The regulator also told the BBC the ruling should serve as a warning to all review sites.

"This should be regarded as a benchmark ruling which applies to all web sites which make claims about the reliability of their user-created content," the ASA's spokesman Matthew Wilson told the BBC.

TripAdvisor says it has "confidence that the 50 million users who come to our site every month trust the reviews they read, which is why they keep coming back to us in increasingly larger numbers to plan and have the perfect trip".