Students arriving at the university's Hawthorn campus on Monday morning were confronted with an illustration of a skeletal man wearing a t-shirt reading "Gay and Proud", with a bullet through his head. The poster, which included a Swastika, was titled "Get the sodomite filth off our streets".

Fairfax Media has chosen not to name the people behind the poster. They claim to belong to an organisation that has no online history. This could be the work of as few as one person.

The posters were stuck onto the university's walls on the day of an annual gay pride event, which included a pride march and a speaking session featuring former High Court judge Michael Kirby and Victoria's Gender and Sexuality Commissioner Rowena Allen.

It also came the day before Opposition Leader Bill Shorten is due to outline his final position on the marriage equality plebiscite to the ALP caucus before the party adopts a formal stance – almost certainly for a free vote in Parliament as the only way forward.

The university's security officers ripped down most of the posters overnight, and pasted flyers promoting the student-led gay pride event in their place.

A Swinburne spokeswoman said they notified police about the incident and extra security was in place for Monday's event.

She said the university had zero tolerance for prejudice, hate and discrimination towards LGBTI people.

"Swinburne prides itself on a diverse and inclusive community, with staff and students from an array of beliefs, genders, ethnicities and identities," she said.

The Swinburne Student Union's queer officer, Joshua Briers, said about 20 homophobic posters were still on the university's walls on Monday morning, but were soon taken down by concerned students and staff.

Mr Briers, an outspoken critic of the plebiscite, said he feared that debate about the public vote had "aggravated" far-right groups.

"I think it has definitely aggravated central elements of the community to be more vocal.

"This makes people feel unsafe in their own community, but what was awesome was to see students and staff and security put up [gay pride] posters saying 'love conquers hate'. We managed to overcome that hate."

Rachael Hambleton, co-convenor of the Victorian Gay & Lesbian Lobby, warned a plebiscite will "give more of a platform to discrimination".

"The idea of a public vote has already brought a debate on the rights of LGBT people into the streets, schools and our homes," said Ms Hambleton, citing the ongoing attacks on the Safe Schools program and homophobic graffiti on posters for Greens candidate Jason Ball.

Margaret McDonald, chief executive of Cobaw Community Health Service which runs WayOut, a suicide prevention program for young LGBTI Victorians, said clients were "really concerned about the whole debate around the marriage equality bill ... and the potential division that it's causing."

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