King Charles faced shouts of "you are not my King" from an independent senator just after he finished an address at Australia's Parliament House on the second official day of his engagements in the country.
Lidia Thorpe interrupted the ceremony in the capital city of Canberra by shouting for about a minute before she was escorted away by security.
The King had just walked away from a lectern to rejoin Queen Camilla sitting on the stage when Thorpe started shouting as she walked forwards from the back of the assembly.
After making claims of genocide against "our people", she could be heard yelling: "This is not your land, you are not my King."
The ceremony was then concluded without any reference to the incident, and the royal couple proceeded to meet the public who had waited outside the building to greet them.
While outside, the King paused to pet an alpaca wearing a small crown. People waving small Australian flags had been queueing outside Parliament House all morning in the punishing Canberra sun.
Jamie Karpas, 20, said he didn't realise the royal couple were visiting on Monday, adding: “As someone who saw Harry and Meghan the last time they were here, I’m very excited. I think the Royal Family are part of the Australian culture.
They are a big part of our lives.” Meanwhile, CJ Adams, a US-Australian student at the Australian National University, said: “He’s the head of state of the British empire right – you’ve got to take the experiences you can get while in Canberra".
A small number of dissenters had also gathered on the lawn in front of the Parliament House building.
King Charles and Queen Camilla had touched down in Canberra earlier in the day and were greeted by a reception line made up of politicians, school children and Ngunnawal Elder Aunty Serena Williams, a representative of the Indigenous people.
Australia is a Commonwealth country where the King serves as the head of state. Thorpe, who is an independent senator from Victoria and an Aboriginal Australian woman, has long advocated for a treaty between Australia’s government and its first inhabitants.
Australia is the only ex-British colony without one, and many Aboriginal and Torres Strait Islander people emphasise that they never ceded their sovereignty or land to the Crown.