Some 500 defence personnel from the Townsville area took part in a military exercise at the centre of a federal election voting controversy, documents show.
The Liberal-National Party is considering a court challenge over the tight election result in Herbert - a north Queensland seat based on Townsville, which is home to thousands of defence personnel.
The seat, previously held by the LNP's Ewen Jones, was won by Labor's Cathy O'Toole by 37 votes.
Defence has previously said 628 army members taking part in Exercise Hamel in South Australia didn't cast their votes but declined to say how many were from the Herbert electorate.
AAP has obtained, via a freedom of information request, an email trail in which Defence tells the Australian Electoral Commission how many personnel would be on the exercise and where they were based.
The "key participating forces" included 200 personnel from Townsville's 3rd Brigade and 300 from the city's 16th Brigade.
The emails bring into question Defence's estimate of how many personnel cast their ballots.
Defence said 1274 voted at polling stations in the exercise area and 1371 were transported to polling stations in Port Augusta, Whyalla, Port Pirie and Kadina.
But the emails to the AEC say the number of personnel taking part was around 9000.
Personnel came from not only Townsville but Darwin, Brisbane and Sydney.
The AEC was told in one email, written by a member of the exercise planning team Major Jeremy Webb on March 30, special voting facilities would be needed because "the nature of the exercise is such that personnel will be deployed in the field, within a tactical scenario, that will prevent them from being able to present to an election booth and/or post office during the two-month timeframe (June-July)".
The final email dated April 6 said the AEC would "work through some options" for the July 2 election.
Voting facilities were rolled out across the exercise area.
But soldiers have told AAP of problems with accessing absentee ballot papers for Herbert, long travel times to get to booths and long waits to vote.
