SINGAPORE — About 665,000 Marina Bay Sands (MBS) shoppers had their data accessed by an "unknown third party" last month, the integrated resort operator revealed on Tuesday (Nov 7).

In an email to customers seen by TODAY, MBS' chief operating officer Paul Town said that the breach on Oct 19 and 20 affected the Sands LifeStyle rewards programme.

Mr Town added that MBS "does not believe membership data from our casino rewards programme, Sands Rewards Club, was affected".

MBS was first aware of the incident on Oct 20, and "immediately took action to resolve it", Mr Town said.

Responding to TODAY's queries, MBS said that the personal data accessed included customers' names, email addresses, mobile numbers, countries of residence and their membership numbers and tiers. 

"Based on our investigation, we do not have evidence to date that the unauthorised third party has misused the data to cause harm to customers," Mr Town said in the email. 

"After learning of the issue, we quickly launched an investigation, have been working with a leading external cybersecurity firm, and have taken action to further strengthen our systems and protect data," he added.

The integrated resort has also reported the incident to the relevant authorities in Singapore and other countries where customer data is affected, and is working with them.

“It is best practice to monitor your account for suspicious activity and change your log-in pin regularly, and to be extra vigilant against phishing attempts, particularly against clicking on links that may direct you to malicious websites where your password or other personal information may be requested,” added Mr Town.