Controversial film Ken Park was turned off by police as more than 500 people crammed into a Sydney town hall Thursday night in support of the screening of the banned film.
A large group of police walked on stage and seized a DVD copy of the film that film critic Margaret Pomeranz was encouraged by the crowd to play.
The independent film was refused classification in May because of its depictions of teenage sex, incest and auto-erotic asphyxiation.
Audience members expressed dismay over the actions of the police.
Earlier, as audience members entered the Balmain Town Hall, they were told by organisers the film wouldn't be screened.
But after a unanimous vote Ms Pomeranz decided to start the movie.
"We're here tonight to see a film that literally millions of people around the world at this very moment have the right to see and a couple of hundred million more in North America will have in the next day or so."
The opening credits began before police seized the DVD.
Police took details from Ms Pomeranz and three other organisers who had supported the film's screening, but no arrests have been made.
The convenor of the Film Classification Review Board Maureen Shelley says there are good reasons for the banning of the film, because of the cumulative impact of scenes showing depictions of actual sex, sexualised violence and child sex abuse.