Some Indigenous leaders have criticised an Australian senator’s heckling of King Charles, as she faces a backlash over a violent image of the monarch briefly posted to her social media account.

Lidia Thorpe, an Aboriginal woman, made global headlines when she shouted “you are not my king” and “this is not your land” before being escorted away from a royal event in Canberra on Monday.

The independent senator’s protest has been praised by some activists as brave, but condemned by other prominent Aboriginal Australians as “embarrassing” and disrespectful.

Thorpe has defended her actions at the event, but said a cartoon later posted to her Instagram account was inappropriate.

The drawing – which depicted the King beheaded alongside his crown – was shared by a staff member without her knowledge, the senator said.

“I deleted it as soon as I saw. I would not intentionally share anything that could be seen to encourage violence against anyone.”

The image, which has drawn condemnation, adds to heavy scrutiny of her actions on Monday.

Aunty Violet Sheridan, an Aboriginal elder who formally welcomed the King and Queen Camilla to Ngunnawal country, told the Guardian Australia: “Lidia Thorpe does not speak for me and my people, and I’m sure she doesn’t speak for a lot of First Nations people.”

Nova Peris – a former senator who was the first Aboriginal woman in parliament and is a long-time republican – also called Thorpe’s actions “embarrassing and disappointing”.

“Australia is moving forward in its journey of reconciliation… as hard as that journey is, it requires respectful dialogue, mutual understanding, and a shared commitment to healing – not divisive actions that draw attention away from the progress we are making as a country,” she wrote on X.

However, other prominent Indigenous activists have lauded Thorpe’s stand.

Vanessa Turnbull-Roberts, a Bundjalung lawyer and author, said there was “nothing more harmful or disrespectful” than inviting the monarchy to tour the country in the first place, given its history.

“When Thorpe speaks, she’s got the ancestors right with her.”

Speaking on Tuesday, Thorpe said she disrupted the King’s parliamentary welcome ceremony after repeated written requests for a meeting and a “respectful conversation” with the monarch were ignored.

She told the Australian Broadcasting Corporation she “wanted the world to know the plight of our people in this country” and for the King to apologise.

“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.

A chorus of Australian politicians including Prime Minister Anthony Albanese have also criticised her protest, and UK Prime Minister Sir Keir Starmer has defended the monarch.

When asked by reporters if it was “disgraceful” for Australian politicians to shout at the King, Sir Keir replied: “Look, I think the King is doing a fantastic job, an incredible ambassador, not just for our country, but across the Commonwealth.”

“He is out there doing his public service notwithstanding the health challenges he himself has had.”

Albanese said Thorpe had not met “the standard behaviour Australians rightly expect of parliamentarians”, while opposition leader Peter Dutton called for Thorpe to resign.

“I really don’t care what Dutton says,” Thorpe told ABC radio in response.

“I’ll be here for the next three years so get used to truth-telling.”