RIOT police broke up a heated clash between gay marriage supporters and their opponents in Martin Place, Sydney.

Hundreds were involved in the rowdy stand-off after supporters of both sides rallied on the streets, waving placards and banners.

But trouble flared when about 200 gay marriage supporters descended on a group of "sanctity of marriage" supporters - organised by the Christian Democratic Party - who had gathered to protest against changing the law.

Scores of police, including the riot squad, stood between the groups as they exchanged a war of words. Trouble escalated when "sanctity" marchers thrust placards at their opponents.

"They were trying to hit us with their signs and were calling us freaks and sinners," one gay marriage supporter said.

Fearing a fight, police forced the gay marriage supporters to Hyde Park where they had organised a march through the city to Darling Harbour - site of the Labor Party's national conference.

Labor back same-sex marriage



Earlier, a motion to change the party platform on same-sex marriage was carried on voices and another motion allowing Labor MPs a conscience vote on the issue was carried 208 votes to 184.

Senator Wong said the "man and woman" in the street would recognise the decision taken at the Australian Labor Party's national conference in Sydney today.



She said it was now a matter for Opposition Leader Tony Abbott to show the same respect for marriage equality.



"The question will be now, for those Liberal members who believe they are actually liberals, whether they will take this up as well," Senator Wong said.



Federal minister Stephen Smith said it would be difficult for Mr Abbott to deny his MPs a conscience vote.



"I'm not so confident that a change will be rejected by the parliament," he said.



"I think Tony Abbott will find it very hard to impose his will on all his members."

Gay marriage vote disappointing - Nile

Christian Democrat leader Fred Nile expressed his disappointment and said one-time ALP luminaries such as John Curtin "turning in their graves"



Mr Nile, who headed a rally against same-sex marriage as the vote was taking place, said he was not surprised by the result.



"I thought it would happen, going by the lobbying and the penetration of the Labor Party by homosexual activists and homosexual individuals," he said.