Fresh doubts have been raised over the federal election result in the north Queensland seat of Herbert.
Labor candidate Cathy O'Toole won the seat from sitting Liberal National Party member Ewen Jones by 37 votes at the 2016 election, leaving Malcolm Turnbull with a single-seat majority in the lower house.
Concerns were raised at the time that patients at Townsville Hospital were unable to cast their ballots and some military personnel on exercise in South Australia may have missed out on a vote.
However the LNP decided against challenging the result in the courts, saying it had "exhausted its enquiries".
Former Herbert MP Peter Lindsay has written to the parliament's electoral matters committee, which meets in Townsville on Tuesday, to raise concerns about "improper voting practices" on Palm Island, about 30km off the north Queensland coast.
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Mr Lindsay said the island of about 3000 residents had seen "continuing questionable elections", including one previous poll where a party offered voters McDonald's restaurant vouchers and T-shirts on their way in to the booth.
He said at that 2016 election Labor volunteers had advised voters the electoral system had changed and offered to help fill in ballot papers, in breach of the electoral act's privacy provisions.
"If 19 voters had voted differently, the LNP would have won the seat and the question of a hung parliament would have been put beyond doubt," Mr Lindsay said.
In another written submission, Townsville Hospital's Dr Craig Costello said he had been told by a colleague three weeks after election day that as many as 39 sub-acute care unit patients missed out on voting.
A nurse had been assured a mobile voting team would attend the hospital, but was advised the team was "really busy" and could not make it before the polls closed.
Mr Lindsay said Palm Island, which had about 800 voters, had a history of voting irregularities which required action by the electoral commission.
"Australians expect the AEC to maintain the integrity of elections," he told AAP on Monday.
"There is clear evidence there would have been a different outcome."
