The guidance covers search rankings, reference prices, hidden charges and pressure selling and must be implement by September 1st, 2019.

OTAs must now prominently inform customers if the money they earn on bookings or "clicks" affects the order of results the customer sees. Presenting discounts by using “strikethrough” prices or savings claims – must be on a “like for like” basis. And statements about availability must tell the whole story, for example "XX people have viewed this property in the last 30 minutes for different dates."

Related: Booking.com, Expedia & Co were misleading users