The Australian Electoral Commission (AEC) will ask federal police to investigate about 8,000 cases of multiple voting from last year's federal election.

The commission has told Senate Estimates it is part of a tough new approach - in comparison, just 19 multiple votes from the 2010 federal election were referred to the Australian Federal Police (AFP).

Senate Estimates has heard 2,000 people have admitted voting more than once, citing reasons including being drunk, confused or "trying out the system".

A further 6,000 people have not adequately explained why they voted multiple times.

Acting Electoral Commissioner Tom Rogers says the AEC will refer all those cases to the AFP, which may then hand matters on to the Director of Public Prosecutions.

"Previously when someone gave us one of those reasons, we accepted those and in many cases did not refer those to the AFP," he said.

"The point of the new policy [is] that may well be a reason but frankly it's irrelevant in terms of the act.

What is multiple voting? Multiple voting is when a person attends more than one polling place on election day or votes more that once using early or postal voting.

Multiple voting is when a person attends more than one polling place on election day or votes more that once using early or postal voting. Multiple voting may also be voting more than once by both voting in their own name, and also voting in the name of another person or persons.

Multiple voting may also be voting more than once by both voting in their own name, and also voting in the name of another person or persons. For example, in addition to casting their own vote, a person may go to a polling place, claim to be another person whom they know is on the roll for that division, have that person’s name marked off the certified list, and cast another vote

For example, in addition to casting their own vote, a person may go to a polling place, claim to be another person whom they know is on the roll for that division, have that person’s name marked off the certified list, and cast another vote Multiple voting is a type of electoral fraud and can result in six months’ imprisonment. Source: Australian Electoral Commission

"So all of those are being referred to the AFP regardless of reason provided. I expect that many of those will be genuine."

About 10,000 multiple votes have been attributed to official error.

Last month, the Senate election in Western Australia was re-held after results from September's election were declared void when about 1,400 ballots disappeared during a vote re-count.

The missing ballots led to the AEC re-examining its security procedures and to an inquiry by former AFP chief Mick Keelty.

Dozens of people at an aged care facility in Perth had to vote a second time in the election re-run because of a problem with a ballot box.

The AEC said an unsecure ballot box used at the facility meant the ballots were invalidated.