AFL chief executive Gillon McLachlan revealed the league's stance on the polarising issue in response to a letter from Geelong woman Sharyn Faulkner, who has a gay son.

"If the AFL publicly declares that they are in support of marriage equality you will give that young player who is struggling with their sexuality the courage to realise just who they are," Ms Faulkner wrote.

In response, Mr McLachlan wrote that football was no place for homophobia, and gave his personal commitment to "continue to speak out in this area whenever I can."

"The AFL will keep saying no matter how many times it takes, that our game does not tolerate discrimination in any form, be that sexual identity, gender, race (or) religious views ... we also support the position of marriage equality for all people.

"This matter is a serious issue for many young gay people, in terms of how they are treated in the wider community, and football leaders such as myself will continue to say that we do not tolerate it, and will continue to push for a change in behaviour from all sections of society."

Ms Faulkner applauded the AFL boss for his response, and said she hoped AFL club presidents would follow his lead.

"The AFL's policy of having no tolerance to discrimination in any form was heartening and for them to actually say that they support 'the position of marriage equality for all people' will make it so much easier for people to say 'if the AFL and my football club can say no to discrimination and yes to equality, so can I'," Ms Faulkner said.

The national director of Australian Marriage Equality, Rodney Croome said that the AFL's support for marriage equality would be welcomed by many AFL players and fans, and would "in all likelihood draw new fans to the game."

"AFL is central to Australian identity and the AFL's support for marriage equality reaffirms that values like inclusion and fairness are central too," Mr Croome said.

Liberal Democrat Senator David Leyonhjelm is preparing a private member's bill to legalise same-sex marriage.

While Labor MPs have a free vote on the issue, the Liberal Party is yet to confirm its position on same-sex marriage in the new Parliament.

While Mr Abbott's firm personal view is that marriage should be between a man and a woman, he has said the question of whether there is a free vote on the issue within the Liberal Party would be a matter for the post-election party room.