The price regulator said in a statement that it had contacted the US-owned platform to seek an amicable solution, but that the effort had been unsuccessful “despite intense negotiations”.

The watchdog said that after an analysis, it had concluded that “the commission rates applied by the company to Swiss hotels were abusively high”.

It ordered Booking.com to lower its commission rates by almost one quarter on average within three months.

The measure aims to “enhance the competitiveness of Swiss hotels in an environment of intense international competition, while indirectly reducing the financial burden borne by customers of the platform”, the watchdog said.

Booking.com, headquartered in Amsterdam and a Dutch subsidiary of US travel group Booking Holdings, said it would appeal to Switzerland’s federal administrative court.

It stated that its commission rates would not change until a ruling was made.

“Our accommodation partners have a multitude of ways to market their properties to customers, so it’s a choice if they want to list on our platform or somewhere else,” it said.

“We do not agree with forcibly reducing the cost of a product that is entirely optional” the company added.

HotellerieSuisse, the employer’s group for the sector in Switzerland, welcomed the regulator’s ruling, calling it “a strong signal” not only for hotels in the country but also for Europe more broadly.

It said it would now study “how, and to what extent” commissions paid could be compensated.