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 customers' data may have been compromised in a cyberattack on Qantas, the airline confirmed in a statement to shareholders this morning.The airline said the cyberattack occurred on Monday after a cybercriminal targeted a customer call centre and gained access to a third-party customer servicing platform.