Sensitive information about Australia's defense programmes has been stolen in an "extensive" cyber hack.
About 30GB of data was compromised in the hack on a government contractor, including details about new fighter planes and navy vessels.
The data was commercially sensitive but not classified, the government said.
It did not know if a state was involved.
Australian cyber security officials dubbed the mystery hacker "Alf", after a character on TV soap Home and Away.
The breach began in July last year, but the Australian Signals Directorate (ASD) was not alerted until November.
The hacker's identity is not known.
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