MELBOURNE • Australia's High Court rejected two legal challenges yesterday against a proposed postal ballot on whether to legalise same-sex marriage, clearing the way for a vote on an issue that has wide support but which has also threatened to divide the government.

Australians will now begin voting in the non-compulsory ballot as early as next week, with a result expected some time in November.

The court's decision to reject the legal challenges, both of which argued that the centre-right government needed the support of Parliament to hold the ballot, comes as a welcome relief for Prime Minister Malcolm Turnbull.

Mr Turnbull supports same-sex marriage, as do two-thirds of Australians, but his government holds a razor-thin majority and more conservative elements in his Liberal-National coalition have used the issue to threaten his leadership.

"Every Australian can have a say and we can, as a Commonwealth of Australia, embrace this important social change," Mr Turnbull told Parliament in Canberra after the court's decision was announced.

If the majority of Australians vote "yes", the government will hold a free vote in Parliament on the issue, with MPs not bound by party policy or the postal ballot's result.

If there is a "no" outcome, there will be no parliamentary vote.

Although the court's verdict provides a viable pathway to same-sex marriage, advocates fear an escalation in an already vitriolic campaign.

The voluntary postal vote was strongly opposed by many gay marriage supporters, who said it would be expensive and divisive, subjecting gay people and their families to hate speech.

Activists fear a surge in malicious campaigning for the ballot, which is not a formal election and is therefore not subject to the usual rules on political advertisements.

REUTERS, AGENCE FRANCE-PRESSE