Almost 1,100 hotels in the Netherlands have joined a European mass claim against website Booking, hospitality industry group Koninklijke Horeca Nederland (KHN) told broadcaster NOS on Friday.

The hotels are seeking compensation because they were not allowed to offer cheaper overnight stays on their own websites than on the booking platform. In total, more than 15,000 hotels across Europe have signed up to the claim, according to the European trade organisation Hotrec. Hotels had until Friday to register.

KHN said it cannot confirm the next step, but if legal proceedings are launched they are likely to be heard in the Netherlands, since Booking.com’s headquarters are in Amsterdam.

Booking.com has said it will challenge the claim. “We are not planning to settle,” a spokesman told NOS.

The mass claim follows a ruling by the European Court of Justice last year which found that Booking could not impose price restrictions on hotels.

KHN and Hotrec estimate that hotel owners could claim back 30% or more of the commission they paid to the platform, provided they can prove the agreements existed.

Booking no longer requires hotels to match its prices.