More than half of eligible Australians have already voted in a non-binding postal survey on legalising same-sex marriage.

The nation began voting on September 12 on whether to change its law to allow same-sex couples to wed. 

The survey is due to finish on November 7.

If a majority of Australians support same-sex marriage, Prime Minister Malcolm Turnbull has promised that Parliament will debate amending the Marriage Act.

The Australian Football League has been a longtime supporter of same-sex marriage, and recently the National Rugby League, Cricket Australia and the Australian Rugby Union have pledged their support for the movement.

The Australian Olympic Committee has refused to join them, however, because it does not want to offend religious groups, chief executive Matt Carroll admitted last month.

"I'm not ducking anything," Carroll said. 

"I'm just saying there are two sides to this discussion and I'm respecting both sides of this discussion. 

"People's religious views are important and they should be respected."

The CGA, though, have come out in support. 

"Commonwealth Games Australia is strongly committed to our core values of Inclusiveness, Respect, Excellence and Integrity," they said in a statement on their website.

"We celebrate the fact that our teams past, present and future have been and will be diverse and representative of all Australians.

"Commonwealth Games Australia has led the way in working with the Gold Coast organising committee to ensure 2018 will represent the most inclusive Commonwealth Games in history.

"This includes equal medal opportunities for men and women, and the most comprehensive integrated Para-sports program in history.

"Commonwealth Games Australia respects the rights of all Australians to have their say in the current postal vote on marriage equality, just as we respect the rights of our member sports to express their own views.

"However, it Is important that as we assemble our team for Gold Coast 2018, our athletes and the broader Australian community understand that we are an organisation that stands strongly by its values of inclusiveness and respect.

"Commonwealth Games Australia is proud to support YES for marriage equality."

The Commonwealth Games Federation, whose Executive Board started a two-day meeting here today, have backed their support for the CGA stance.

"We’re proud of @CommGamesAUS as they promote inclusiveness and respect in support of marriage equality in Australia," they said on their official Twitter feed.

Homosexuality remains illegal in at least 26 countries and territories due to take part in next year's Commonwealth Games in the Gold Coast.

In Nigeria and Uganda it is still technically possible that a man can be executed if he is found to have engaged in a relationship with a member of the same sex.

Earlier this year a female badminton player who represented Uganda at the 2014 Commonwealth Games in Glasgow was granted asylum in the United Kingdom.

Margaret Nankabirwa and partner Lydia Nabukenya claim they had feared for their lives since 2014 after they were discovered in bed together in the former’s home.

They were "outed" by a neighbour of Nankabirwa after she had returned from competing at Glasgow 2014.

Nankabirwa was able to board a plane to London the same day she was discovered, using a valid travel visa from competing in Scotland.

She lived alone on the streets of England’s capital before Nabukenya was able to join her.

Other countries due to take part at Gold Coast 2018 where homosexuality is still illegal include Antigua and Barbuba, Bangladesh, Barbados, Bostwana, Cook Islands, Ghana, Guyana, India, Jamaica, Malaysia, Kenya, Kiribati, Pakistan, Papua New Guinea, Saint Lucia, Saint Kitts and Nevis, Saint Vincent and the Grenadines, Samoa, Sierra Leone, Singapore, Solomon Islands, Sri Lanka, Trinidad and Tobago and Tuvalu. 

Glasgow 2014 undertook several initiatives during the last Commonwealth Games to promote lesbian, gay, bisexual and transgender (LGBT) rights.

This included Glasgow City Council flying the LGBT flag during the Games and support for Pride House, welcoming LGBT athletes, officials and spectators during the event.