Police in Victoria have discovered what appears to be a major security breach involving classified files from ASIO, West Australian Police and the state's Office of Police Integrity.
Police say the documents were found during a drug raid at the home of a former employee in suburban Melbourne earlier this month.
The ABC reports details of what police found there were revealed on Wednesday morning.
Victoria Police issued a statement saying the ASIO papers related to a job application.
It is believed the man who was the target of the drug raid was in a relationship with a former senior employee of the OPI.
The OPI says the documents were apparently in the possession of its former head of intelligence. Documents from ASIO and West Australia's Corruption and Crime Commission were also found.
No-one has been charged with possession of the files, but police say a number of people have been charged over the drug raid.
Former head of the National Crime Authority, Peter Faris QC, says it is a major security breach which should be investigated by federal authorities.
"Well it could hardly be more serious. I'm stunned by it," he said.
"Goodness only knows what other material is available elsewhere or is out in the criminal community."
