Same-sex marriage legalised in Australia as Parliament passes historic law

Australia has officially become the 26th country to legalise same-sex marriage after the law passed on Thursday with the resounding backing of the Federal Parliament.

Thirteen years after changing the Marriage Act to explicitly forbid same-sex unions, federal politicians voted to undo the last major piece of discrimination against gay and lesbian Australians.

It followed last month's emphatic resolution of the Australian public in the postal survey to join the rest of the English-speaking world by embracing marriage equality.

The vote in the House of Representatives on Thursday came after last week's vote in the Senate, meaning the law has now passed both houses of Parliament.

Fairfax Media understands a special meeting of the Executive Council has been called for Friday morning for the Governor-General to officially sign the bill into law.

When the vote was declared on the floor of the House, the packed public gallery exploded into cheers and applause, while MPs crossed the chamber to embrace each other - and in some cases, cry.

Numerous well-known gay and lesbian Australians were present to witness the historic moment, including Olympic swimmer Ian Thorpe and actress Magda Szubanski.

"Many of us older LBGTIQ people never thought we would see this day," Szubanski said earlier from outside Parliament House.

"When we were young, it would have been zero per cent of people who would have voted for marriage equality.

"It was inconceivable - but today, Australia, you've demonstrated you love us. We love you."

While gay rights campaigners have fought for marriage equality for decades, the direct path to Thursday's vote began two years ago when the former Abbott government announced it would settle the question of same-sex marriage by a public plebiscite.

Prime Minister Malcolm Turnbull continued that policy, but it was blocked by opponents in the Senate. The government later opted to hold a voluntary postal survey asking: "Should the law be changed to allow same-sex couples to marry?"

Australians voted "yes" to that question by 61.6 per cent to 38.4 per cent, prompting the government to allow a free vote in Parliament, which passed on Thursday.

Attorney-General George Brandis indicated it could be about one month before same-sex couples can have legal weddings, due to administrative issues.