Anti-gay campaigners are spreading materials that label homosexuality as a "curse of death" and make false claims about children being raised by gay parents.
It comes as Australia prepares for a non-binding postal vote on marriage equality.
Posters have been found in Melbourne and Sydney that contain slogans like "stop the f*gs" and feature illustrations of figures holding rainbow weapons.
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The posters also feature a false claim that 92 percent of children of gay parents suffer abuse, according to The Guardian.
Leaflets have also been found in mailboxes in the Sydney suburb of Hurstville, calling homsexuality "a tragedy" and "a grave to the family bloodline".
LGBTI advocates have called on Prime Minister Malcolm Turnbull to condemn the material, and said that the postal vote on marriage equality was spurring extremist and hateful views in Australia.
Just Equal spokesman Rodney Croome told The Guardian "The hate displayed in these posters will shock and disgust the overwhelming majority of Australians."
Labor leader Bill Shorten opposed the Prime Minister's decision to hold the non-binding postal vote, saying that it would unfurl "filth" and "hatred" and "vilify and demean LGBTI Australians and their children".
New Zealand legalised same-sex marriage in New Zealand in 2013, MPs voted 77 - 44 in favour in Parliament to pass a bill put forward by Labour MP Louisa Wall.