Sensitive information about Australia's F-35 stealth fighter and other military hardware was stolen during a cyber-attack last year, it has emerged.
About 30 gigabytes of data was stolen - including details of the Joint Strike Fighter aircraft and P-8 Poseidon surveillance plane.
Australia's defence industry minister, Christopher Pyne, told ABC Radio: "Fortunately the data that has been taken is commercial data, not military data... it's not classified information.
"I don't know who did it."
Mitchell Clarke, an official from the Australian Signals Directorate (ASD), said technical information on smart bombs and several naval vessels was also stolen.
He added that the "compromise was extensive and extreme".
The hacker gained access to a small contractor's systems for a period of five months in 2016. They used a tool known as "China Chopper", which security experts say is widely used by Chinese hackers.
Mr Clarke said the "methodical, slow and deliberate" choice of target suggested a nation-state was behind the cyberattack.
He said the hacker has been nicknamed Alf, after a character in the Australian soap opera Home And Away.
Australia has agreed to buy 72 F-35A aircraft for €11bn.
Mr Pyne said Australia has experienced an increase in cyberattacks at a time when it is carrying out a $39bn (€25.7bn) submarine project.
Earlier this week, it emerged Australia has been subjected to 47,000 cyber incidents in the last 12 months - a 15% increase on the previous year.