Same-sex marriage advocates say a confronting poster in Melbourne shows how hurtful and "mean spirited" the debate is becoming ahead of a national postal vote on the issue.
The anti-LGBTI poster, seen in Heffernan Lane, says "Stop the fags" with an image of two hands holding rainbow coloured belts and a child sitting with its head down.
The poster includes statistics credited to Donald Paul Sullins, a priest at Catholic University of America whose research has been widely discredited.
The sign, which has been shared widely on Twitter, includes claims: "92 per cent of children raised by gay parents are abused. 51 per cent have depression. 72 per cent are obese."
Victorian Human Rights Commissioner Kristen Hilton said the poster was deeply offensive and inaccurate.
"It looks like [this type of message] is set to continue and I think that's a really disturbing trend," she said.
"I think that people need to call that out and condemn this type of material.
"Yes, people are entitled to have different views, but in a debate like this it's really important to convey those views respectfully."
Voters urged to keep 'a very inquiring mind'
Ms Hilton said the statistics have no scientific basis and called on the public to be cautious of false information as the debate becomes more intense.
"I think it's really important to have an open mind and to question the evidence and the position that is put forward," she said.
"The most recent review by Columbia Law School earlier this year looked at 79 different studies into the well-being of children with gay or lesbian parents.
"That study, the most comprehensive of its kind, found kids [with LGBTI parents] do as well [as other children] emotionally, educationally and socially.
"So in the midst of what is a very heated and passionate debate, because it concerns the rights of people and it concerns their right to marry and a right to equality, I think it's really important to keep a very inquiring mind about positions that are put forward."
Ms Hilton said the only way to avoid a lengthy, damaging debate causing harm to LGBTI people, is to resolve the issue as quickly as possible.
Federal Opposition Leader Bill Shorten condemned the poster on Twitter.
"I'm sorry that LGBTI Australians have to put up with this. Let's make sure there's an overwhelming 'Yes' vote in response," he wrote.
Council has not seen poster in other parts of Melbourne
Parents and Friends of Lesbians and Gays national spokeswoman Shelley Argent said seeing the poster would be painful for LGBTI people.
"It's got to be pretty distressing for them," she said.
"For young people who are in the process of coming out, or for children who may have same-sex parents, it is just awful."
It is not known who put the poster up or whether there are more around the city.
Melbourne City Council said it had not seen any and had sent an officer to Heffernan Lane, but the poster was no longer there.
The council, which supports same-sex marriage, said it would remove offensive graffiti or posters.
Australian Christian Lobby managing director Lyle Shelton, who is a high-profile campaigner against same-sex marriage, said on Twitter he was "happy to condemn" the poster.
The Federal Government has scheduled a postal vote on same-sex marriage to be held from September 12 to November 7.