A flood of suspect reviews are contaminating travel website TripAdvisor and boosting the ratings of hotels across the world, it is claimed.
The revelations mean that millions are booking holidays and business trips on the basis of bogus five star recommendations, according to research by Which?
The consumer champion analysed almost 250,000 reviews and found that one in seven of some 100 popular hotels carried TripAdvisor recommendations that had blatant hallmarks of being false.
Which? has reported 15 of the worst cases to TripAdvisor and the company admitted that 14 of these had already been caught with fake positive reviews in the last year.
The consumers' group and the Competition and Markets Authority have identified a wider problem of fake reviews on websites on everything from household appliances to handymen services. Online reviews influence an estimated $44billion of transactions a year in the UK alone.
Some of the most troubling findings concerned hotels in Las Vegas and the Middle East. In one case TripAdvisor had to remove 730 of the five-star ratings for the 'best hotel' in Jordan. Which? said some of the best-rated hotels in London, Paris, Barcelona and Cape Town also gave some cause for suspicion.
Naomi Leach of Which? Travel said if sites such as TripAdvisor failed to ensure their information was reliable, they should be 'compelled to make changes so holidaymakers are no longer at risk of being duped by a flood of fake reviews'.
TripAdvisor said the Which? analysis was 'based on a flawed understanding of fake review patterns and is reliant on too many assumptions, and too little data'.