The ABS’ second weekly update on the survey’s progress revealed 62.5 per cent of eligible voters – or about 10 million people –  have participated voluntarily.

It is an increase of 800,000 surveys from the same time last week.

A higher percentage of Australians have now taken part in the survey than Irish people in their country’s 2015 marriage referendum.

Almost two-thirds of Irish voters favoured marriage equality.

Sally Rugg from left-wing lobby group GetUp said the result was evidence of a “huge public energy” in the campaign. 

“We know the majority of Australians support marriage equality - that’s been the case for a decade - so we’re cautiously optimistic that today’s update is a good sign,” Ms Rugg said.

“Every good result, big or small, inspires our volunteers and supporters to keep working until every Yes vote is posted, and until a bill has passed Parliament.”

The high turn-out follows 100,000 new voters joining electoral roll in a last-minute surge before the postal ballots were sent.

In Bendigo, 550 people aged under 24 joined the electoral roll in the lead-up to the survey.

The ABS estimate is indicative only, based on the bulk containers of returned forms – not a count of individual surveys.

It also does not include forms that have been posted but not yet delivered to the ABS.

Weekly updates will be provided until the survey closes on November 7. Results are due for release on November 15. 

No campaigners were also active on Tuesday, with a grass-roots crowdfunding campaign reputedly behind the word “no” in the sky above Melbourne.