An Australian soldier and her husband have been arrested and each charged with spying for Russia.
Investigators said the couple, who are Russian-born Australian citizens, had obtained Australian Defence Force (ADF) documents and shared them with Moscow.
However, Australian police said they had not found any “significant leaks” of military secrets.
It is the first time that Australia’s tougher foreign interference laws, introduced in 2018, have been used in a case of espionage.
Army Private Kira Korolyov, 40, and her husband Igor Korolyov, 62, are due to appear in Brisbane court on Friday each charged with conspiring to commit espionage, which is punishable by up to 15 years in prison.
Australian Prime Minister Anthony Albanese said he had received an “extensive briefing” from the country’s security services but did not comment directly on the case as it is currently under trial.
Australian Federal Police (AFP) Commissioner Reece Kershaw said the couple had been in Australia for more than 10 years prior to the alleged incident and both became Australian citizens several years ago.
Police said Igor was self-employed and Kira was an information systems technician in the Army and held security clearance for her job.
Ms Kershaw alleged that she had secretly travelled to Russia whilst on leave from the Australian Defence Force and then instructed Igor to access her work account and send her classified material, which he then forwarded to Russian authorities.
Kershaw said the investigation into whether those materials were actually given to them was still ongoing and that the charges could be more severe.
Both Kershaw and Australia’s top intelligence official, Mike Burgess, spoke to media on Friday and did not answer questions about the nature of the documents or how authorities became aware of the alleged crimes.
But Mr Burgess said the ongoing threat of espionage was “real”.
“There are countries trying to steal Australia’s secrets. We cannot afford to be complacent or complacent.”
“If you are espionage in this country, we are looking for you. If you are the subject of espionage in this country, we are keeping an eye on you,” he added.
Kershaw stressed that Australia’s allies can “have confidence” that Australia will “continue to identify and disrupt espionage and foreign interference activities”.
The ADF said in a statement it was aware that one of its members had been arrested and that it “takes any security breaches seriously”.
