Indigenous Senator Lidia Thorpe has justified her roundly criticised protest action against the King, saying she had written to the monarch multiple times and he ignored her.

Thorpe made headlines around the world for interrupting the royal reception at Parliament House on Monday and on Tuesday defended her behaviour after critics labelled it “disrespectful”.

Thorpe said her repeated written requests for a meeting and a “respectful conversation” with the monarch had been ignored.

“That wasn’t afforded to me, so I did that for my people. I did that for my grandmother, and I wanted the world to know that we need a treaty here and we want an end to this ongoing war against first peoples in this country,” she told ABC radio.

“I don’t subscribe to assimilating myself into the colonial structure.”

Thorpe doubled down on her accusation that the King was complicit in the genocide of Indigenous people by remaining silent.

“Why doesn’t he say, I am sorry for the many, many thousands of massacres that happened in this country and that my ancestors and my kingdom are responsible for that,” she said.

In an interview on British Sky News’ Breakfast program, Thorpe was asked several times why she had called the King a “genocidalist”.

In her questioning, host Kay Burley pointed out that the King had “acknowledged, recognised grievances in his speech” but “you interrupted him and called him a genocidalist”.

“Why is this the best way to deal with this?” Burley said.

Thorpe responded pointedly that she “did not once interrupt his speech, I respectfully waited right until the end”.

But Burley cut her off, asking again: “Why did you call him genocidal, why did you call him genocidal?

And a third time: “Why did you call him genocidal?”

Thorpe said there were “thousands of massacre sites” in Australia from “invasion” and “someone needs to answer for that and he is the successor, then he needs to answer”.

Thorpe said she had interrupted the King for “truth telling” about the royals who “cause so much devastation to not only our people in this country but Indigenous people around the world”.

“We don’t have a treaty in this country. We’ve been calling for decades and decades for a treaty. We just want peace,” she said.

“We have jails full of Aboriginal people, 23,000 Aboriginal children taken from families, over 600 deaths in custody … no one held accountable.

“We have our bones and our skulls still in his possession – or in his family’s possession.

“We want that back, we want our land back, and we want your king to take some leadership and sit at the table and discuss a treaty with us because treaty is what will bring us peace.”

Thorpe insisted to Burley that the King “is not our sovereign. The King lives in your country”.

The independent from Victoria confronted the King and Queen at a welcome reception at Parliament House on Monday, before being kicked out.

“You are not our king. You are not sovereign,” she shouted.

“You committed genocide against our people. Give us our land back. Give us what you stole from us — our bones, our skulls, our babies, our people.

“You destroyed our land. Give us a treaty. We want treaty.”

Thorpe demanded the UK hand back Indigenous artefacts and remains that had been taken.

Opposition Leader Peter Dutton labelled her protest an act of “self-promotion” and said she should consider resigning.

“People need to express themselves respectfully and sometimes people make it all about themselves and I think that’s what yesterday was,” he told the ABC.

Labor minister Amanda Rishworth said Thorpe’s actions were “pretty disrespectful and not just to the King, but to the many great Australians that had gathered in the Great Hall”.

NSW Premier Chris Minns, who hosted a community barbecue for the royal couple on Tuesday, said Thorpe’s protest was “grossly disrespectful”.

“Everything that particular Senator does seems to revolve around herself, as if she’s attempting to make herself, that Senator, the focus of all attention,” he told Sydney’s 2GB radio.

The Coalition is considering raising a censure motion against Thorpe in the upper house when it next sits in November.

-with AAP