A spokesperson for the National Cyber Security Centre said:
“We are working with partners to better understand the data breach affecting Marriott International and how it has affected customers.
“The company has confirmed an unauthorised access to a database they say contains information on up to approximately 500 million guests worldwide who made a reservation at a Starwood property.
“The NCSC website includes advice for people who think they have been affected by the data breach, including guidance on suspicious phone calls and targeted emails that can be sent after a data breach.
“We also recommend that people are vigilant against any suspicious activity on their bank accounts and credit cards and contact their financial provider if they have concerns.”
If you have any concerns please call us on +44 1481 742074, or email firstname.lastname@example.org.