Far-right and far-left extremists are on a violent collision course in a capital city, as rival protest groups plot to clash with each other at upcoming rallies.
Police said "gutless" troublemakers among the demonstrators will use protests as an excuse to pick a fight, warning of extended delays in moving around for anyone else in Melbourne's CBD on Saturday.
Rallies for the same causes have been planned around Australia but other police forces have not warned of similar plans for clashes.
Victoria Police has intelligence those with far-right and extreme ideologies, as well as far-left and opposing views, will seek conflict and confront each other.
Friction is expected between the two sides as well as within each group.
Flyers promoting the left-wing protest say it was prompted by an attack on Camp Sovereignty on 31 August, when dozens of men dressed in black stormed King's Domain where the remains of Indigenous people from 38 clans are located.
Earlier that day, some 20 people were arrested when anti-immigration and counter-protesters clashed in the city.
Neo-Nazis attended the anti-immigration protest and a prominent figure addressed a crowd of thousands of people on the steps of state parliament.
Victoria Police Superintendent Troy Papworth said the safety of Camp Sovereignty on Saturday was "front of mind" for the force and extra officers would be in the city, but did not reveal where they would be stationed.
He said investigators cannot discount the chance neo-Nazis will again take to the streets, even though a leader in their group is behind bars.
"We're also well aware of other people within that group who are willing to step up into that person's shoes," the superintendent told reporters at police headquarters on Wednesday.
'Veiled excuse to punch on'
Papworth said people are sick of protesters using rallies as a "veiled excuse to punch on" and described the behaviour as gutless.
He said individuals targeted officers with hostile behaviour during the clash in late August.
"We saw people throwing projectiles, not only at opposing protest groups, but also at police," he said.
"Bottles of fruit liquid being thrown at police, and that's something we simply will not tolerate both towards our police and towards anyone in the community."
Victorian Premier Jacinta Allan said no one has the right to use the "cloak of a protest to bring violence to our streets".
"Victoria Police will deal with that behaviour," she said.
Police have extra powers to search people for weapons in the CBD on Saturday and can direct people to remove face coverings.
