TORONTO - Canadians have started receiving emails from Marriott International, informing them of a recent breach of customers' personal data held by their Starwood hotel properties.

The U.S.-based hotel giant, which is also behind brands including W Hotels, St. Regis, Sheraton and Westin, says in the email that the breach may have impacted up to 500 million guests.

The company says the contact information, passport numbers, arrival and departure information, reservation dates, and credit card information of up to 327 million guests may also be entangled in the incident.

Marriott says unauthorized access to such data has been occurring since 2014, but was only recently discovered.

Marriott says it has been sending emails with these details to guests since Nov. 30, when the breach was revealed.

The company did not respond to a request for comment regarding how many Canadians have, or are expected to, receive the emails.