Milo Yiannopoulos' visit to the Australian city of Melbourne has caused violent clashes between anti-fascist and hardline right-wing groups.
Dozens of officers in riot gear were involved in subduing the unrest that took place outside a venue where the broadcaster was speaking in the suburb of Flemington.
One police officer suffered minor injuries to the lower body after being hit by a rock and two people were arrested for "discharging a missile".
Yiannopoulos, born in the UK and now based in the US, is a notorious, self-described troll who has courted controversy by defending paedophilia, and promoting racist and misogynistic views.
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During his Australian tour, he has amused audiences by ridiculing Indigenous Australians as "losers of history", saying anyone in the country who identifies as Muslim should be sent to the Middle East and making crude, offensive remarks about feminist writer Clementine Ford.
He has also labelled former Prime Minister Julia Gillard a "prick" and attacked Australian The Project host Waleed Aly and his wife for being Muslim.
Extra security measures are being taken at Parliament House in Canberra, where Yiannopoulos has been invited to speak on Tuesday (local time) by Liberal Democrat Senator David Leyonhjelm.
The Australian Greens unsuccessfully attempted to have him banned from the building.
Victoria Police assistant commissioner Stephen Fontana says "Kardashian-style politics" is causing the protests to turn violent.
"We've always got Kardashian-style politics now, and these people know that you have to do something outrageous in order to get it on to YouTube and seen across the world," he told Melbourne radio 3AW on Tuesday.
"I've got no doubt part of their motivation last night was to get as much as they could splashed around the world and feel famous for five minutes."
Yiannopoulos said the protests indicate Australia has "a serious problem with free speech".