Harper's protest is an echo of former NFL quarterback Colin Kaepernick kneeling to protest police brutality. He originally sat during the national anthem.
"When it says 'Advance Australia Fair,' it means advance the white people,” Harper told 9 News, describing the anthem's lyrics. “And when it says 'we are young' it completely disregards the indigenous Australians who were here before us for 50,000 years.”
The incident and remarks drew criticism from politicians, including former prime minister Tony Abbott, who suggested it signals “good manners” to stand while the anthem plays.
Australia's indigenous population of 2 million is plagued with higher unemployment, compared with the general population, a lower life expectancy by a decade and higher rates of suicide, obesity and alcoholism.
Queensland Sen. Pauline Hanson, a far right nationalist politician who represents Harper's state, has long been critical of extending resources to indigenous Australians. She took to social media and expressed outrage and blamed Harper's parents.
"It's about who we are as a nation, it's part of us,” she said in a video Wednesday. “Here we have a kid who's been brainwashed. And I'll tell you what, I'd give her a kick up the backside.”
Jarrod Bleijie, a shadow education minister and member of the Queensland Parliament, accused Harper's parents of using their daughter as a “political pawn” and urged her to stop the protest.
"Refusing to stand disrespects our country and our veterans. Suspension should follow if she continues to act like a brat,” he said on Twitter.
Harper's father, Mark Nielsen, on 9 News called his daughter a “very brave young person” for taking a stand.
In a statement, the Queensland Department of Education said it was inclusive and supported different points of view, but denied Harper was threatened with suspension or exclusion for her protest.
"The school has been respectful of the student’s wishes and has provided other alternatives including remaining outside the hall or not singing during the national anthem,” the department said.
Her mother, Yvette Miller, said the school's reaction was too severe, News 9 reported.
"We were surprised behavior such as a passive nonparticipation might be considered in the same realm as something like bringing a knife to school or being violent toward others,” she said.