A group of protesters attempted to stop Dr Don Brash from speaking at an Auckland University-hosted free speech debate tonight.

Dr Brash was about to start his first speech on how PC culture is damaging free speech in New Zealand when a woman with a megaphone began yelling at him, surrounded by supporters holding flags and banners.

"We stand against racism, Don Brash represents hate," she said as some people booed her from the other side of the auditorium.

Dr Brash then managed to speak as the cacophony died down.

"They don't want to debate the issues they just want to shout us down, PC culture shuts down free speech," Dr Brash said.

Hate speech is not free speech the protesters shouted back, once again interrupting proceedings as they also yelled "Don Brash go home."

Dr Brash supporters then chanted his name until he was allowed to speak.