Hundreds of soldiers from Darwin and Adelaide taking part in war games in outback South Australia did not vote last Saturday in the federal election.

Key points: Thousands of soldiers participating in Exercise Hamel war games

Thousands of soldiers participating in Exercise Hamel war games Plan was to have mobile polling booths

Plan was to have mobile polling booths Number of booths cut back, leaving hundreds unable to vote

Plans to cover their voting needs fell way short, prompting a large-scale effort to truck military personnel into nearby towns.

The 1st Brigade - from Darwin and Adelaide – had been taking part in Exercise Hamel. It was Australia's biggest defence exercise for the year, involving more than 8,000 people.

The plan was to have soldiers rendezvous mid-battle at seven mobile polling booths on Saturday to vote in the election.

But the booths were cut back to four on the day. While some - including a brigade mascot – got to cast a vote, hundreds more did not.

In a statement, an Australian Electoral Commission (AEC) spokesperson said the number of planned polling booths had been reduced to where soldiers "were able to rendezvous".

"Clearly, the overall circumstances of this special event – mid-exercise – were large-scale, complex and dynamic," the statement said.

"The AEC acknowledges that it appears some enrolled ADF members may not have been able to vote."

Hundreds of members did not vote

On election day, Defence said just under 1,300 ADF members voted at the special polling stations in the exercise area, but that the Army had to truck another 1,400 or so to civilian booths in places such as Port Augusta.

Defence said AEC staff and volunteers stayed back for up to three hours - until 9pm - to process the huge lines.

But it still was not enough.

In a statement Defence said: "628 Army members did not cast their votes. Of this number, 543 are from the 1st Brigade."

Those numbers are not enough to have changed the outcome in the Darwin seat of Solomon or the Adelaide seat of Wakefield, where the 1st brigade is based.

But the new Solomon MP designate Luke Gosling, a former army member, said it was a shame if members of the ADF had not been able to vote while on exercise.

"For them, to have the opportunity to cast a vote would be important," Mr Gosling said.

He said most in Defence were interested in the federal outcome and would be deployed overseas by the government of the day.

"To a large extent (they would be) helping other people and other countries enjoy the same sorts of freedoms that so many Australians sometimes take for granted."

There has been a strict phone blackout during Exercise Hamel, but the ABC has spoken with family members reporting some soldiers are angry at missing out on their right to vote.