"The election was called unexpectedly and at the fag end of the holiday period you'd expect people not to be paying much attention," he said.

"What we don't know is whether this reflects a concerted effort by political parties to enrol people, whether they've used social media and direct mail to drive up that number - which is possibly what the Labor party would do in key seats...

"That would explain it, but I don't know that's the case."

Almost a third of those who updated their details were under 24. Of them, 8800 were aged between 18 and 19, and 11,000 were aged between 20 and 24.

Both Labor and the LNP say they had not made any extra efforts to convince young voters to enrol beyond what they did before the 2012 election.