More than 18,000 Aussies under investigation for voting twice at federal election

More than 18,000 Australians have been investigated for voting twice or more at the nation's federal election held on July 2, 2016.

The Australian Electoral Commission (AEC) told a Senate estimates hearing Tuesday night that 18,343 Australians have formally been asked to explain why their names might have been "ticked off" twice, with 59 people asked to explain why it seems they voted three or more times.

Australians who are convicted of voting more than once in the election face hefty fines of up to 7,500 U.S dollars, while some could face the prospect of jail for one year.

Surprisingly, two Australians were marked off on 11 separate electoral roles and two were marked off five times, while four voters were ticked off four times and 51 Australians apparently voted on three different occasions.

AEC Commissioner Tom Rogers told the Senate estimates hearing that New South Wales had the most number of multiple voters with 6,760, while Victoria and Queensland had 4,800 and 2,792 cases respectively.

The New South Wale figure almost eclipsed the total from the 2013 election, in which 7,743 cases were referred to federal police. Tellingly, just 65 of those were investigated further, while no convictions came of the investigations.

Rogers said a select few voters who had been marked off two or more times at the past two elections had been sent unique warning letters reminding them of their obligations on election days.

"We wrote to a select group of people we thought may be at risk of not understanding their obligations under the Electoral Act," he told the Senate estimates hearing.

"We've never done that before. That was an attempt to demonstrate the seriousness with which we treat this particular issue."

Rogers said the issue of multiple voters at this year's federal election was treated very seriously, considering some crucial swing seats were decided by less than 1,000 votes. Endit