The voting rate in the same-sex marriage ballot reached 62.5% as of last Friday, according to the latest estimate of the Australian Bureau of Statistics.
The rate has already topped the participation rate in the 2015 Irish referendum, which was 60.5%.
The ABS, in its update on Tuesday, said it estimated it had now received 10 million ballots. This was 800,000 higher than the previous number a week earlier.
The numbers are based on the bulk containers of returned forms, not on a count of individual ballots.
The vote runs until November 7 and the results will be released on November 15. Opinion polls are pointing strongly to a win for the “yes” campaign.
The Anglican Diocese of Sydney this week disclosed it had given A$1 million to the “no” campaign.
The Sydney archbishop, Glenn Davies, said in his presidential address to the diocese’s synod on Monday: “The stakes are high and the cost is high. Yet the cause is just and it is a consequence of our discipleship to uphold the gift of marriage as God has designed it – a creation ordinance for all people.”
The “yes” campaign on Tuesday urged those who had not yet voted, including people overseas, to do so. The co-chair of the Equality Campaign, Anna Brown, said: “There are still millions of surveys that need to be posted back to the ABS.”