Several fiery outbursts have marred an otherwise peaceful Australia Day, with an Australian flag set on fire in Sydney and Melbourne protesters likening the holiday to celebrating the bombing of Hiroshima.
Thousands of indigenous Australians and their supporters marched in major cities across the country arguing January 26 shouldn't be celebrated because it's actually "Invasion Day" for many.
Melbourne protester Michael Polanske says it's a day of mourning for Aboriginal people.
"We don't celebrate September 11, we don't celebrate Hiroshima - it's pretty stupid to celebrate today," he told AAP at the rally attended by about 3000 people.
"I'd just like it moved (to a different date)."
In Sydney a heated scuffle erupted between police and several protesters at an "Invasion Day" march after an Australian flag was allegedly set alight.
Footage on social media shows police officers and protesters shoving each other with some falling to the ground.
A 20-year-old man was arrested and taken to Redfern police station for questioning.
One officer was injured and taken to hospital, while a woman suffered minor injuries and was hospitalised as a precaution, a police spokeswoman told AAP.
The scuffle was an "isolated incident in an otherwise peaceful demonstration", she said.
Police estimate thousands attended the Sydney event.
NSW Premier Gladys Berejiklian was quick to condemn the unrest.
"I'm so disappointed people couldn't express themselves in a more appropriate way on such an important day," she told reporters.
Brisbane's annual protest was conducted peacefully with about 1000 people marching.
Members of the local Aboriginal community voiced grievances about the British "invasion" in 1788, deaths in custody and poor education.
"We need to get our own land back, where we came from," Brisbane man Charles Hegarty said.
Hundreds in Canberra marched to Parliament House chanting "Always was, always will be, Aboriginal land".
The Canberra protest sent a message that many indigenous people rejected a proposal for constitutional recognition in favour of a treaty.
The Referendum Council appointed by Prime Minister Malcolm Turnbull and Opposition Leader Bill Shorten in 2015 has begun community consultation on constitutional recognition with a final report due later this year.
"What do we want? Treaty. What have we got? F*** all," was one provocative chant yelled by the crowd.