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A row has broken out over the reliability of the hotel-review website TripAdvisor, with hoteliers alleging that the market-leading giant is no longer capable of policing its own content.

With 25m user-generated reviews and opinions on more than 490,000 hotels and attractions worldwide, and with more than 11m registered members, the Expedia-owned website has become a hugely powerful marketing tool, with many hotels admitting that the majority of their bookings come either directly or indirectly via the site.

But in the current grim economic climate, with businesses fighting harder than ever for a share of the dwindling market, a dirty war has broken out with hotels and restaurants using the site to attack rivals or boost their own ratings by posting fake reviews.

Di Beach, who runs the Los Castaños hotel, near Ronda, in southern Spain, is one of the victims. Until a fortnight ago, her property was ranked number one on TripAdvisor’s Ronda listings, a lucrative position that she says brought in “90%” of her business.

But when a rival hotelier allegedly questioned the authenticity of her latest appraisals, TripAdvisor blocked them, posting in their place a critical review that sent her ratings — and her bookings — tumbling.

“What worries me is that this reviewer claims to have stayed here in May 2008,” says Di. “My register says he didn’t. There’s definitely something wrong at TripAdvisor.”

TripAdvisor, which says it catches “the vast majority of fraudulent reviews”, claims every submission is scrutinised by a “team of quality- assurance specialists”, and that hotels caught subverting the system are flagged up with red warning messages.

Although TripAdvisor administrators said they could not say exactly how many properties had been caught abusing the site, a search by The Sunday Times found fewer than 30 red-flagged hotels worldwide, suggesting that either an infinitesimal number of TripAdvisor’s 490,000 featured properties are posting fake reviews or that many more are slipping through the net.

“The system is laughably easy to manipulate,” said a former West Country hotelier who asked not to be named. “We were ranked in the top 10 for the entire summer before I sold the property, and I wrote every single review. I was even approached by PR firms offering to write my reviews for me. It’s not hard to cover your tracks.”

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