Several hundred people gathered at Sydney Town Hall Square on Saturday afternoon - despite given only three days notice - to protest the Howard Government's ban on same-sex marriages, demanding the Government overturn recent Marriage Act amendments, which prevent gays and lesbians from marrying.

Organised by the NSW Gay and Lesbian Rights Lobby, AIDS Council of NSW (ACON), New Mardi Gras and Sydney Pride Centre, the rally heard speaker Retired Uniting Church minister Dorothy McRae-McMahon call on Canberra to stop using gays and lesbians as political pawns.

She also rejected claims that same-sex marriages sent a negative message to the community about family values.

"Why on earth would heterosexual people be so nervous about us threatening their relationships?" she said, referring to the government's justification for legislating to shield the nation's children from the "shocking" sight of two happy mothers with two happy children, according to an Australian Broadcasting Corporation report.

"If families are in trouble at the moment, it's none of our doing.

"It's related to all sorts of complex situations and issues which lie with heterosexual relationships today and, to some extent, with ours as well."

Rally host Stevie Clayton told the crowd the choice to get married should be her own and not John Howard's, while Gay and Lesbian Rights Lobby co-convenor and rally organiser Somali Cerise said the prime minister was trying to turn back time as the federal election loomed.

Cerise addressed the crowd, saying that same-sex couples simply wanted the same rights as everyone else in the community.

"Over the last 20 years gay men and lesbians have fought for equality. Gay sex is legal now. Our relationships have been recognised. Finally we obtained an equal age of consent," she said.

"Australians now know that there is nothing radical about gays and lesbians being treated equally.

"It's all about a fair go.

"Yet, with an election looming, our prime minister has tried to turn back time.

"Last time it was refugees, leaking boats and babies overboard. This time it's lesbian mums in wedding dresses."

Last month, the Government hurriedly amended the Marriage Act to exclude gay couples and ban same-sex couples from adopting children from overseas. For the first time, the bill incorporated a formal definition of marriage in the Marriage Act: "Marriage, according to law in Australia, is the union of a man and a woman to the exclusion of all others, voluntarily entered into for life."

The new bill however allows a surviving partner of an interdependent relationship to claim the death benefit of their loved one and not be forced to pay a death tax on the payment.