They are the grubby prison cells away from home, the matchbox-size rooms with the peeling wallpaper and fetid sheets - at least according to the online reviews. But how bad are they really?

The hotel industry is increasingly concerned at the power wielded by internet sites such as TripAdvisor, on which often excoriating - yet anonymous - notices are posted that can destroy an establishment's reputation.

It comes after hoteliers reacted with fury, claiming their businesses were damaged, after being included in a list of the 10 "Dirtiest Hotels" in Britain, released to publicise the site.

Bob Cotton, chief executive of the British Hospitality Association, said hotels across Europe want the European Union Commission to overhaul the rules governing website reviews to ensure they have been posted by genuine guests and not by rivals or people out to cause mischief.

Cotton said he had had discussions in Brussels on behalf of the industry so "some sort of common sense should prevail".

Perhaps worst hit by an online review recently was the two-star Grosvenor Hotel in Blackpool, which was named in the TripAdvisor survey as Britain's dirtiest establishment.

Its owner, Chirag Khajuria, who has had 3000 guests since taking over the seaside hotel six months ago - garnering just 35 poor reviews - criticised the methodology.

"It all seems very biased in favour of the bad reports, when some of our guests have said they would be back again to stay," he said.

Even when the Daily Mail went to poke fun at the hotel it concluded the £26-a-night ($59) room was "no worse - and, in some cases, better - than many other hotels in Britain".

TripAdvisor said its Dirtiest Hotels list included factors other than the anonymous reviews. It said it used "automated tools" to detect fraud, as a well as a team of moderators.