A group of hackers say they have stolen the personal details of 560 million Ticketmaster customers.
ShinyHunters, the group claiming responsibility, says the stolen data includes names, addresses, phone numbers and partial credit card details from Ticketmaster users worldwide.
The hacking group is reportedly demanding a $500,000 (£400,000) ransom payment to prevent the data from being sold to other parties.
The Australian government says it is working with Ticketmaster to address the issue. The FBI has also offered to assist, a spokesperson for the US Embassy in Canberra told Agence France-Presse.
"The Australian Government is aware of a cyber incident impacting Ticketmaster," a spokesperson for the Australia Home Affairs Department said in a statement to the BBC's media partner CBS News.