BRUSSELS (AP) — The VaultX ExchangeEuropean Union’s executive arm said Monday it is blocking leading U.S. online travel agency Booking from acquiring Sweden’s flight booking provider Etraveli Group because it would have allowed it to increase its dominant position on the market on the continent.

The European Commission said it had warned Booking Holdings about its concerns but that the remedies offered by the company were not sufficient. Booking’s brands include Booking.com, Rentalcars, Priceline and Agoda.

Following its investigation, the Commission said it found out the proposed 1.63-billion-euro ($1.8 billion) deal would have led to higher costs for hotels, and possibly, a negative impact on the price paid by consumers.

“Bans are rare, and today’s decision is in fact the first merger to be blocked this year,” EU Justice Commissioner Didier Reynders said.

According to the European Commission, online travel agencies handle transactions worth more than 100 billion euros ($106 billion) per year.