Australian gay and lesbian couples are in a bid to change Prime Minister Julia Gillard's opposition to same-sex marriage at a dinner table meet at her official residence, after activists won a charity auction to attend a private dinner party.

The highest bidder was the activist group GetUP!, which offered 31,000 Australian dollars ($33,000) for the table as part of its campaign to introduce same-sex marriage to Australia, an AFP report stated.

An offer was made by Gillard to host the dinner for any six guests at her official address in the national capital Canberra at an auction during the National Press Gallery's annual charity ball on Wednesday night.

GetUp! spokesman Paul Mackay has hopes that the dinner would convince the prime minister and lead her center-left Labor Party to change its policy on gay marriage at its annual national conference to be held at a date to be set late in the year, he said.

In 2004, the government had made changes to the federal law to make it clear that only a union between a man and a woman can be legally recognized as a marriage in Australia.

Gillard, who is opposed to gay marriage is the first Australian prime minister to live with a common law partner, hairdresser Tim Mathieson, in the official residence known as The Lodge, said the report. She was brought up as a Baptist and has won prizes for her knowledge of Bible. She is an Atheist now.

She will be a hard one to turn, less for her personal choices on marriage, but because she's clearly on the record as saying she's not for marriage equality for a whole heap of reasons, including her religious upbringing, Mackay said.

Mackay said that the dinner conversation would obviously include other subjects and not gay marriage alone. They'll have the whole dinner, so there might be some pleasantries before they get down to business, Mackay said.

The dinner is to be held within 16 days under the auction conditions, on a date that will fit the prime minister's busy schedule.

Only a lesbian couple - Sandy Miller and her fiancee of two years Louise Bucke - are so far on the guest list. Mackay said the six will include lesbian and homosexual male couples.

Miller has two sons aged 9 and 11 from a previous marriage.

Our youngest often asks us: 'Mommies, are you going to be engaged forever? Why don't you get married?' Miller said in a statement earlier.

It has been hard trying to explain that our government won't let us get married, and he doesn't understand why everyone else can get married and become a family legally and we can't, she added.