Former federal police commissioner Mick Keelty has criticised "lax" and "complacent" practices with the Australian Electoral Commission in concluding the fate of 1370 missing Western Australian Senate votes may never be known.
The Australian Electoral Commission asked Mr Keelty to investigate what happened to the ballot papers after the loss of the votes was discovered in October during a recount.
In a report released on Friday, Mr Keelty said while his investigation had not excluded the possibility of criminality, he had not discovered any evidence to suggest it was more likely than that the ballot papers had simply been misplaced.
"It is tempting to say that the ballots are most likely to have been mistakenly destroyed with recycling material but the system put in place by the WA AEC office was so parlous that such a conclusion would be difficult to prove," Mr Keelty wrote.
Mr Keelty found there was no apparent policy or process to cross check rubbish and recycling before disposal to ensure ballot papers were not accidentally thrown out.
He identified a "loose planning culture" and a "complacent attitude" toward ballot papers and "lax supervision" in the AEC's WA operations.
"In the 2013 Senate Election in WA, the AEC failed to meet its own high standards and damaged its reputation with the community and the Parliament," Mr Keelty said.
He discovered within the AEC there was less concern for Senate ballots because of a view that they had less of an impact on the election outcome than those of the House of Representatives. "This is a cultural problem within the AEC and it needs to be addressed," Mr Keelty found.
He recommended a range of changes to AEC policies and systems. The AEC has accepted each of them and will immediately begin to implement them.
The Special Minister of State, Michael Ronaldson, said the report raised "serious concerns about the current practices of the AEC, both in relation to the security of ballot papers, logistics and training".
He said the AEC needed to assure voters in the other states that similar failures had not occurred elsewhere.
"The fundamental responsibility of the AEC is to ensure the security of votes cast by the people of Australia. They rightly would have assumed that the AEC's existing processes and procedures already provided the appropriate level of protection."
"The Electoral Commissioner and the Commission must accept full responsibility for what occurred."
The episode could lead to a fresh vote for WA Senators next year. The Electoral Commission last month lodged a petition with the High Court, sitting as the Court of Disputed Returns, seeking an order voiding the election of the state's six declared Senators.
Palmer United Party leader Clive Palmer has said he intends to lodge a petition asking the Court to uphold the result of the first count, in which his candidate Zhenya "Dio" Wang qualified for a spot.