Australian airline giant Qantas said on Wednesday that it has suffered a data breach that has compromised the personal information of at least six million passengers.

Australian airline Qantas says a data hack on Monday exposed the personal information of six million customers and it expects the amount stolen to be “significant.”

Millions of Aussies have been impacted by the shock cyber hack on Qantas, which extracted sensitive customer data including names, emails, phone numbers, birth dates and frequent flyer numbers.