A number of public servants have been sanctioned over the "extraordinary lapse of security" which led to the release of secret cabinet documents.
In February, the ABC revealed papers covering details of five federal government cabinet meetings over a decade had been unsuspectingly sold off in a pair of locked filing cabinets at a second-hand shop in Canberra which stocked ex-government furniture.
The filing cabinets were unlocked with a drill months later.
The ABC published a number of stories using some of the less-sensitive material, but later returned the documents.
Prime Minister Malcolm Turnbull at the time described the sale of the cabinets as a "disgraceful, almost unbelievable act of negligence".
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His department boss Martin Parkinson on Friday said an Australian Federal Police investigation had found it was the result of a series of human errors in the record-keeping, movement, clearance and disposal of the cabinets by the department in February 2016.
But the breach was not motivated by criminal or malicious intent.
"I have personally dealt with and sanctioned a number of officers for their roles in this security breach," Mr Parkinson said in a statement, noting he had also received a report into security practices by former top public servant Ric Smith.
"Given the personal nature of sanctions, I will not be commenting further on these."
Steps are now in place to digitally track secure cabinets and train officers in security risk management.
"I am deeply concerned that such an extraordinary lapse of security could occur. I am committed to ensuring that such an unauthorised disclosure does not happen again," Mr Parkinson said.
