Lidia Thorpe says she can't be kicked out of parliament for breaching the parliamentary oath she took when she was sworn in because she didn't technically swear allegiance to the crown.

The Indigenous senator, who caused an international stir when she yelled at King Charles III at an official reception at Parliament House on Monday, was asked if that meant she had renounced her sworn parliamentary affirmation to bear true allegiance to the monarch.

"I swore allegiance to the queen's hairs," Senator Thorpe, who was sworn into the Senate in 2022 where she also referred to the Queen as "coloniser", told the ABC.

"If you listen close enough, it wasn't her 'heirs', it was her 'hairs' that I was giving my allegiance to, and now that, y'know, they are no longer here, I don't know where that stands.

"I'm not giving up my job, I'm not resigning."

Senator Thorpe had also signed a written oath before witnesses, which would have spelled the word "heirs" correctly, constitutional law expert Anne Twomey said.

Her action in the Great Hall before the King and Queen has led Nationals senator Bridget McKenzie to question whether the independent firebrand had breached the oath all MPs make to the Crown.

"Senator Thorpe, I think, is the only parliamentarian that I've ever known to disavow their oath of allegiance to our sovereign and their heirs and successors according to law," Senator McKenzie said on ABC radio.

"So what she did on Monday essentially breached that."

Senator McKenzie compared Senator Thorpe's "oath breaking" to an illegal act in a courtroom.

"So if it was happening in a court of law where you breached your oath, that's contempt, that's perjury, that's a criminal offence," Senator McKenzie said.

"And so I think there are some legitimate questions to be asked about this and what is the consequence of Senator Thorpe's action from a constitutional perspective."

But constitutional law experts told NewsWire the prospect of any repercussions for breaking the oath would be an issue as a parliamentary oath and an oath in court are different.

Parliament has the power to censure an MP, but not throw them out.

"Senator McKenzie seems almost to be suggesting that it is wrong for a parliamentarian to advocate for a republic, to argue for getting rid of the monarchy – which is something many people on her side of politics have done," Monash University constitutional law professor Luke Beck said.

"Senator McKenzie is wrong that protest 'weakens our system'."

He said the Constitution included an implied freedom of political communication, which protects protest activity.

"Engaging in protest activity is not a ground of disqualification. Advocating for a republic is not a ground of disqualification," he said.

"Being rude to the king is not a ground of disqualification. Engaging in rowdy politics is not a ground of disqualification.

"Did Thorpe's protest get people talking about the issues she cares about or did it just get everyone talking about her rather than the issues?"

On ABC radio on Tuesday, Senator Thorpe said she yelled at King Charles III for her grandmother, her community and a treaty.

Questioned about the fact she took an oath to the crown when she became a senator, Senator Thorpe said "I don't assimilate to the colonial structures".

"I had to do that (swear an oath) to fulfil my duties. And I can guarantee you I did that under duress and we should not be kneeling to the coloniser."

"My people died fighting for this country and they are the resistance fighters of our people."

"I will be there for another three years. So get used to truth-telling."

The Senator said she had written to the King multiple times without response.

"My approach may upset a few people, but how else do you get your message across when we're continually shut down as blak women."

When the independent Senator was sworn in – as a Greens MP – she walked to the centre of the chamber to recite the oath with her fist in the air.

She called the Queen a coloniser. Other MPs did not like that and Senator Thorpe then repeated the oath as it's written, all the while keeping her fist raised.

Blair Jackson - NCA NewsWire