Australian airline Qantas disclosed that it detected a cyberattack on Monday after threat actors gained access to a third-party platform containing customer data.

The database did not contain financial information, such as credit card numbers, which are stored on different servers, Qantas said on Wednesday. Qantas told the Financial Times it was investigating whether the Scattered Spider cyber criminal group was behind the attack.

Australian airline Qantas has been targeted in a major cyber attack, with millions of customers affected. The airline said it detected “unusual activity” on Monday and the personal data used by Qantas’s contact centre had been compromised.