Neo-Nazi groups have been involved in distributing homophobic material as the marriage equality continues ahead of the postal survey.
Australian white power group Antipodean Resistance, which has a history of Nazi-inspired vandalism, has distributed factually-incorrect posters throughout Melbourne.
"The prime minister needs to be condemning neo-Nazi groups," Shadow Attorney General Mark Dreyfus told reporters in Canberra on Tuesday.
"It's an extraordinary thing that he's just remained silent in the face of ugly statements that have been made in relation to the marriage equality survey."
Anti-semitic and swastika-bearing propaganda linked to the group has been found on university campuses along the east coast, with the homophobic 'no' campaign posters found in Melbourne as recently as Sunday.
Labor MP Matt Thistlethwaite said the opposition had warned such activity from far-right groups would occur if a plebiscite or postal survey went ahead.
"It appears that these organisations are now coming out of the woodwork because we've got this debate going on regarding marriage equality in Australia," he said.
The responsibility for the increasing vocalisation of far-right groups lay with Malcolm Turnbull due to his inability to get a free vote through his party room, Mr Thistlethwaite said.
"Because of that, gay and lesbian Australians have to face this vitriol, this divisive campaign that really they don't deserve," he said.
Two challenges to the postal survey will be heard by the High Court on Tuesday and Wednesday with a ruling expected before postal surveys are sent out on September 12.