The investigation now being launched will examine, among other things, whether the site is doing enough to prevent fraudsters from using it to list fake accommodation and what is being done to combat "phishing" - the fraudulent collection of passwords and other sensitive information. The handling of paid advertisements will also be investigated.
"Europeans must be able to book their holidays without fear of being scammed," EU Commissioner Henna Virkkunen writes in a press release.
According to AFP, Booking.com promises full cooperation and insists that security and the protection of personal information are "top priorities."