The leading website, TripAdvisor.com, now publishes more than 5m reviews. More than 20m people visit the site each month, despite concerns that the internet is riddled with misleading information.

Publishers of traditional guides such as the AA, Fodor’s and Alastair Sawday have already launched their own websites carrying guest reviews, or plan to do so.

But an investigation by The Sunday Times has discovered that hotels and restaurants are drumming up business by posting glowing reviews of themselves.

In the course of the investigation it found:

• Proprietors describing hotels as “outstanding”, “excellent” and “charming” without declaring their interest in the business.
• Marketing executives to top British hotels recommending perks be offered to customers in return for a promise of a good review.
• Hotel star ratings on well-known websites that could be easily “ramped” with just a few e-mails from bogus customers.

The findings add to the concern about the unreliability of some online information. Sir Tim Berners-Lee, the British inventor of the world wide web, recently warned that the internet is in danger of being swamped by untrue and unfair statements.

Among customer reviews included in TripAdvisor was an outstanding endorsement for the Drumnadrochit hotel in Scotland which failed to make clear that it had been written by David Bremner, its proprietor.

It gushed: “My parents stayed many years ago and said what a lovely spot this place has. They were so right! . . . Well done to the staff, who really were charming.” Bremner said last week: “Maybe I shouldn’t have done it . . . I don’t think it’s that big a deal.”

Scott Hessel, another undeclared proprietor, posted a message on a different website raving about his “stunning new pub restaurant” in West Yorkshire. He later said: “It wasn’t my intention to mislead anyone . . . I think it was a bit of a misinterpretation.”

A further site, allinlondon.co.uk, contained a review from one London restaurateur claiming his business offered “amazing value”.

To discover how widespread the practice is, an undercover reporter visited several hotels and restaurants, chosen at random, offering a service writing favourable online reviews.

A Michelin-starred restaurant and one of the world’s top hotels were both prepared to consider the proposition.

Many websites appeared to do little to vet the reviews written by customers. Fodors.com proved easy to manipulate with e-mails.

One London hotel, Vandon House, was slammed by a customer who complained about its noisy rooms and “miserable” beds. It took four glowing e-mails to lift its ranking from a poor 1.2 out of 5 to 4.2, elevating it to among the capital’s top establishments.

Additional reporting: Megan Kaesshaefer

Explore UK News

• Crime News

• Education News

• Health News

• Science News

• Scotland News

Times Recommends

• DIY video helps the WI get to grips with sex
• Artists urge nation to save Titians
• Go home, Iraqi leader tells Britain