Britain's competition regulator said on Friday it would investigate hotel booking websites over its concerns that they did not help people find the best deal and were potentially breaking consumer law.
The Competition and Markets Authority (CMA) said it was concerned about the clarity, accuracy and presentation of information on sites, which could mislead consumers.
Major hotel booking site operators include U.S. companies Expedia, Booking.com,which is owned by The Priceline Group, Hotels.com and Germany's Trivago, which is majority owned by Expedia.
The CMA said it would examine how hotels were ranked, for example whether results were influenced by how much commission a hotel pays over the customer's requirements, and the use of pressure selling, such as claims about how many rooms were left.
It also had concerns over the discounts advertised for the rooms and hidden charges, including taxes and booking fees.
CMA chief executive Andrea Coscelli said around 70 percent of people looking for a hotel last year used the sites and they should all be confident they were getting a good deal.
"To do this, sites need to give their customers information that is clear, accurate and presented in a way that enables people to choose the best deal for them," he said.
"But we are concerned that this is not happening and that the information on sites may in fact be making it difficult for people to make the right choice."
If the CMA finds that sites' practices or claims are false or misleading and are breaking consumer law, it can take enforcement action.
On March 29, a Turkish court ordered the suspension of Booking.com's activities in Turkey involving Turkish hotels, citing accusations of unfair competition, following a lawsuit filed by the Association of Turkish Travel Agencies (TÜRSAB).