Hotel giant Starwood, which operates chains such as Marriott and Sheraton, has been the victim of a very large-scale data breach: information on approximately 500 million guests has been leaked.

The chain stated this in a press release.

According to Starwood's owner Marriott International, an investigation has shown that unauthorized visitors have had access to Starwood's network since as early as 2014.

For about 327 million of those affected, information was available about the customers' names, mailing addresses, phone numbers, email addresses, passport numbers, dates of birth, gender, and personal information related to the chain's loyalty program. In some cases, the information also included credit card numbers and card expiration dates, but the chain said this information was encrypted.

However, there is no information in the press release that information about what guests have seen on hotel TV has been leaked.

Marriott states that the discovery has been reported to the police and that the hotel company will assist in the investigation.

Marriott acquired Starwood in 2016, creating the world's largest hotel chain. The chain's many hotel brands include JW Marriott, Ritz-Carlton, W Hotels, Sheraton, Le Méridien, Westin and Courtyard.