Protesters set upon a bus that was due to take guests to a dinner hosted by the right-wing Q Society in Melbourne.
Protesters have prevented people from boarding a bus to attend a Q Society dinner expected to be attended by former Liberal Senator Cory Bernardi and LNP MP George Christensen.
The protesters chanted slogans and waved signs and jostled the attendees at the St Kilda Marina in Melbourne.
The Age reported the event location was a strict secret to everyone, including the invited guests.
Posts on social media show attendees calling the Q Society organisers directly to try and get the address and others reportedly left the scene in cars.
Other attendees were stuck on the bus, which was initially unable to move due to the protesters. It was able to drive away after about an hour.
The Q Society calls itself a Islam-critical organisation, and it has come under criticism over its extreme right wing views.
Former Liberal MP Ross Cameron copped criticism on Friday for attending a Sydney Q Society fundraising event and allegedly making homophobic comments.
Mr Christensen and Senator Bernardi's plans to attend the dinner were known last month and opposition politicians have called on Prime Minister Malcolm Turnbull to stop them going.
Senator Bernardi was due to give a speech at the event.
The organisation's website says all proceeds of the dinner will go towards the legal expenses of the Q Society and two individuals in a Supreme Court defamation action initiated by Mohamed El-Mouehly of the Halal Certification Authority.
The Q Society's event description for the fundraiser describes the legal contest as a "landmark case with considerable ramifications for freedom of expression".
Tickets to the event cost $150 per head - a price that drew mixed reaction on social media.
- with AAP