Australia's independent election overseer has apologised after more than 1800 missing federal ballot papers were discovered at the home of a transport worker.
The 1866 ballots from the Sydney seat of Barton were counted on election night by Australian Electoral Commission workers and their fate does not affect the outcome of the vote in that electorate.
After the votes were first counted, they were supposed to be delivered to the electoral commission's counting centre for further scrutiny.
The AEC was unable to start with a mandatory second count of the election results because one of the ballot containers hadn't been returned. All of the others were accounted for.
An authorised transport officer had "inadvertently maintained possession" of the missing container, the commission said.
"It was recovered from the transport officer fully intact, with all uniquely coded security seals unbroken, and without any damage," a spokeswoman said in a statement.
"All ballot papers were still in the recovered ballot paper transport container and were promptly returned to the counting centre and have undergone fresh scrutiny.
"The fresh scrutiny count matched the initial count and the election in the Division of Barton was unaffected by this incident."
Labor retained the seat of Barton, with Ash Ambihaipahar replacing the retiring Linda Burney.
While the commission is investigating the incident, it doesn't believe the transport worker deliberately held on to the ballot container.
"This shouldn't have occurred, and the AEC is deeply concerned that on this single occasion our process did not prevent the issue on polling night when ballot papers were initially returned," the spokeswoman said.
"Work is already underway to further investigate this incident to understand what, if any, elements of the return of materials process need to be changed for future elections."
The electoral commission said security measures and ballot tracking meant the AEC was quickly able to determine that not all ballot papers had been returned.
"The AEC takes ballot paper handling extremely seriously and deeply regrets this incident," the spokeswoman said.
"The AEC's manual processes inherently rely on people and occasionally people make mistakes or don't exercise the best judgement, particularly when under pressure."
Second counts of all electorates are carried out to ensure accuracy with the final election result.
