Australian same-sex couples could wed by Christmas following the country overwhelmingly voting in favor of changing federal marriage laws.

Of Australians eligible to cast a ballot in the postal survey, 61.6 percent said "yes" to amending the definition of marriage whereas 38.4 percent responded "no," according to the Australian Bureau of Statistics.

Turnout for the voluntary poll, an anomaly for Australian politics which usually compels participation, was 79.5 percent, with 12,727,920 votes cast nationwide.

Women took part more than men and those between 70 to 74 years voted more than any other age group.

Despite the resounding result, Australia's Marriage Act will not automatically be modified.

But Prime Minister Malcolm Turnbull promised to bring legislation before Parliament by Christmas in a video message posted to Twitter shortly after the outcome was made public.

"The people of Australia have spoken and I intend to make their wish the law of the land by Christmas. This is an overwhelming call for marriage equality," Turnbull tweeted Wednesday.

The survey was controversial for members on both sides of the debate due to its high cost and nonbinding nature.

The survey was seen as a way to gauge popular opinion as Turnbull's coalition government would not agree to a parliamentary conscience vote on the issue. Political parties in Australia typically vote en bloc.