An Italian court overturned Monday a 500,000-euro ($550,000) fine slapped on TripAdvisor for failing to warn users that some opinions posted on the popular hotel and restaurant review website may be fakes.

"TripAdvisor never asserted that all the opinions were real, even mentioning that verification was impossible and to consider the trend rather than each comment one by one," said the administrative court ruling.

Italy's competition watchdog slapped the fine on the local subsidiary of the popular travel website in December, saying the company's advertising had emphasised "the authentic and genuine nature of the reviews, persuading consumers to believe the information is always reliable and reflects real tourist experiences."

Italy's hotel and restaurant trade association, Federalberghi, expressed its disappointment in the court ruling, which it said confirms that gaps in the country's legislation allows the company to avoid correcting its practices.

Federalberghi cited the recent case of a phantom restaurant leaping to the top of the rankings in a Lombardy town in one month thanks to 10 fake comments.