SYDNEY - Queen Elizabeth's representative in Australia has officially signed same sex marriage into law following a landmark vote in the federal parliament. The first weddings can take place in a month's time (Jan 9).

The passing of the historic same sex marriage bill Thursday prompted songs and celebrations in the Australian parliament. The new law brings to an end more than a decade of bitter debate on the issue. MPs voted to change the Marriage Act and bring to an end a ban on gay and lesbian couples marrying.

The landmark measure became official when Governor-General Peter Cosgrove, who represents Australia's head of state, Britain's Queen Elizabeth, signed it into law.

Gay couples will be allowed to marry in a month's time because in Australia authorities must be given four weeks' notice before any wedding takes place.

Australia's center-right Prime Minister Malcolm Turnbull says it is a momentous occasion.

"What a day! What a day for love, for equality, for respect,' said Turnbull. 'Australia has done it. Every Australian had their say and they said it is fair - get on with it! And the parliament has got on with it and we have voted today for equality, for love. It is time for more marriages."

The bill to amend the Marriage Act was first introduced into parliament last month, immediately following a national poll that showed about 62 percent of Australians supported change. Critics said that a law to legalize gay marriage would expose children to radical views on homosexuality in the classroom. The bill includes exemptions for religious celebrants, who can refuse to marry same-sex couples on the basis of their faith.

Couples who have married overseas in countries such as Canada and Britain will automatically have their marriages recognized in Australia.

The famous sails of the Sydney Opera House have been illuminated in pink and rainbows to celebrate the historic vote.