Statue of Queen defaced with red paint as King Charles tours Australia

The iconic statue of Queen Victoria in Sydney's CBD has been defaced with red paint in a suspected protest against King Charles and Queen Camilla's tour of Australia.

Police are investigating the incident in which red paint was splattered across the statue outside the Queen Victoria Building in the early hours of Tuesday morning. 

CCTV footage from the area is expected to help identify those responsible.

The incident comes just a day after independent Senator Lidia Thorpe challenged the King during a welcome reception in federal parliament.

At the gathering in Parliament House in Canberra, the Victorian politician told the monarch he was not her king. 

'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.' 

The King and Queen, who were still seated on the stage during the confrontation, appeared to take no notice as the King turned to speak to the prime minister and Camilla. 

Charles and Camilla have faced low-key protests during their tour of Australia, from supporters of First Nations resistance to colonisation, who have been displaying a banner with the word 'decolonise' at a number of events. 

Labor minister Amanda Rishworth said Senator 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'.

'We're pretty shocked and didn't quite understand why this was going on, so it was very disrespectful,' she told Nine's Today program.

'But it didn't put a dampener on ... the very positive rest of the welcome ceremony, which I think was really very positive.'

Nationals MP Bridget McKenzie said she was appalled.

'If you're not a fan of King Charles and Queen Camilla, don't accept the prime minister's invitation,' she told Nine.

The federal Opposition is considering raising a censure motion against Senator Thorpe in the upper house when it next sits on November 8.