Australians have demanded politicians allow same-sex couples to marry, delivering a landslide victory to the ‘Yes’ campaign in the national postal vote on marriage equality.

Thirteen years after the Howard government changed the law to prevent same-sex marriage, Australians have now backed the historic social reform, with 61.6 per cent voting ‘Yes’ to 38.4 per cent for ‘No’. The turnout was 12,727,920 people (79.5 per cent).

The result was announced by Australia’s chief statistician David Kalisch at 10am on Wednesday.

Gay couples will not be able to marry until Parliament passes legislation to enact the reform, but the government expects this will happen before Christmas.

On Tuesday, a group of cross-party senators backed a same-sex marriage bill penned by Liberal Senator Dean Smith.

It is anticipated that Senator Smith’s bill will be introduced into the Senate on Wednesday afternoon, with debate to begin on Thursday, though it is expected to be subject to numerous amendments.

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Government conservatives led by Victorian senator James Paterson, who supports same-sex marriage, have called for increased protections for speech and religious freedom.

Mr Turnbull has indicated the government would “not countenance” winding back anti-discrimination laws.

Prime Minister Malcolm Turnbull returned from the ASEAN summit in the Philippines for the result on Wednesday morning.

Labor Senator Penny Wong, who has co-signed Senator Smith’s bill, said Senator Paterson’s proposal was a “distraction”.

“If there is a Yes vote today I don’t think it can be spun by conservative politicians that that was a vote to extend discrimination rather than being a vote to lessen discrimination,” Senator Wong told ABC radio before the result.

But conservatives are likely to argue the case for more protections during parliamentary debate over the coming days.

“I don’t agree with the Prime Minister that this (James Paterson) bill makes activities which are currently illegal legal,” Nationals Senator Matt Canavan told ABC radio.

The postal survey, which cost $122 million, was an attempt from the Turnbull government to fulfil its election promise for a plebiscite on the social reform.

Same-sex marriage advocates, as well as the Labor and the Greens, opposed the survey.

Australia is the second country to hold a popular vote on the reform after Ireland, which backed same-sex marriage through a constitutionally required vote in 2015.