Police have been called to the University of Sydney after a rally encouraging students to vote "no" in the same-sex marriage postal survey drew hundreds of counter-protesters.
About 200 students gathered around a few students who were making speeches and holding signs that read "It's ok to say 'no.'"
The confrontation occurred shortly after midday on Thursday near a stall that is believed to have been set up by the university's student-run Catholic society.
Kishor Napier-Raman, 21, who is a law student at the university and an editor of the student newspaper Honi Soit, said, "The Catholic society tried to have a 'vote no' rally with the promise of free kebabs, but it seemed to have been quickly surrounded by a much bigger counter-rally.
"There were maybe 15 'vote no' people there and hundreds of 'vote yes' people. [The counter-rally] had a megaphone and the 'vote no' people were saying things like, 'You're drowning out our voices,' " Mr Napier-Raman said.
"There was a bit of kerfuffle, people were shouting at each other and the man with the sign was trying to approach bystanders.
"The counter-rally people were trying to get in his way and were arguing with him.
"I heard that there was one person who made a comparison between same-sex marriage and paedophilia and someone said, 'Why can't I marry my dog?' It was a bit ridiculous."
A spokesman for the Sydney University Catholic Society said that "vote no" campaigners were "physically assaulted, verbally abused and repeatedly shouted down".
"We were told we cannot be on campus with such beliefs...we maintain that university is a place where different opinions can and should be expressed without fear of safety," the spokesman said.
Videos of the protest show a large crowd chanting, "Hey hey, ho ho, homophobia's got to go" on one of the university's central walkways and a brief physical altercation being broken up by police.
Mr Napier-Raman said he saw as many as 10 police officers and campus security guards at the protest.
A NSW Police spokeswoman said officers were called to the university at 12.35pm.
"There was quite a heated verbal confrontation, the worst was someone putting a megaphone in someone else's face," Mr Napier-Raman said.
Another student posted a photo of police holding a man's arm and said that a "scuffle" over one of the "vote no" signs turned violent and police were pulling protesters away.
Mr Napier-Raman said he wasn't aware of the original 'vote no' rally and was only alerted to the protest after he saw a video of the large crowd on Facebook.
"I saw it on Facebook and I thought that I'd better get there," he said.
Mr Napier-Raman said that this was the first protest against same-sex marriage he had seen on campus.
A spokeswoman for Sydney University said: "We understand that a number of people protested in favour and against same-sex marriage.
"The University of Sydney expects that any expression of views on this matter is conducted in a respectful manner."
