Police have notified a group of protesters aligned with the sovereign citizen movement occupying a space outside of Old Parliament House that they need to move on by Friday afternoon, ahead of protesters' plans to storm the building on Saturday.
An ACT Policing spokesperson said they were "following a request from the National Capital Authority to remove structures and vehicles that are on Commonwealth land without a permit".
"While the operation is ongoing, ACT Policing is asking the ACT community to avoid the area if possible," the spokesperson said.
"Further information will be provided once the operation is complete."
The National Capital Authority has been contacted for comment.
The protest group, which has established a self-styled embassy, is not associated with the Aboriginal Tent Embassy, which has condemned the group's actions.
In social media footage posted by protesters on Friday afternoon, police can be heard advising people in the camp it is an offence to camp on Commonwealth land without a permit under a 1932 ordinance.
The ordinance, which predates self-government in the ACT, allows the Commonwealth to remove people found to be trespassing on national land, which includes the Parliamentary Triangle.
The Trespass on Commonwealth Lands Ordinance 1932 gives the federal government the power to appoint inspectors who can remove people suspected of trespass.
The ordinance allows for those inspectors, or police officers, to arrest without a warrant anyone reasonably suspected of trespass who refuses to give their name and address.
"Any tents, caravans, vehicles and other camping equipment must be removed by 4pm or police may remove and take custody of these items," police told protesters over a loudspeaker.
Bruce Shillingsworth snr, a protest leader, earlier responded to police using a megaphone, telling the officers they needed to put their request in writing to the camp.
"We are on our original land. We are not the trespassers. You are the trespassers. You have trespassed this land for 233 years. I am willing to take this to the High Court to prove that you're wrong," Mr Shillingsworth said.
"Where are your deeds and titles? Where is the bill of sale? There is no bill of sale. This land was never sold. This land was never sold ... we would ask you to leave. You're making our children scared. You are committing a crime. You are committing genocide. If you wish to speak us or contract with us, please put it in writing."
Police established a perimeter around the campsite just before 3pm.
Some protesters could be seen disassembling tents, though the camp remained largely intact.
The protest group, which has camped in an area behind the National Rose Gardens since mid-December, has been linked to a fire at Old Parliament House and confronted police on a number of occasions.
A man from the group who identified himself as Jeffrey, a Darumbal-Gungulu man from Central Queensland, said he did not plan to move on. He said he was a sovereign national and when asked about the groups anti-vaccination sentiment said they were "pro-choice".
Social media posts from members of the group and supporters have circulated in the lead-up to January 15, calling on people to gather outside of Old Parliament House in Canberra to evict the Australian government, and establish a people's council.
"I'm all about being honest ... and on Saturday we plan to go through them doors," one of the protesters said in a video on social media posted in recent days.
Elders in the Aboriginal community have accused the "anti-vax" camp set up alongside the long-standing Aboriginal Tent Embassy of being a health risk to the whole of Canberra, and said the people should be moved on.
Discussions were understood to be underway at least a week ago about how to remove the group from the parliamentary triangle.
Authorities were concerned by a planned build up of protesters and anti-government activists at the site in the lead-up to the 50th anniversary of the Aboriginal Tent Embassy on Australia Day, January 26.
Footage posted to social media from participants at the camp shows people sharing discredited information about COVID-19 vaccinations and views in common with the sovereign citizen movement.
The group believes Australian government has no jurisdiction on the land and the power of the police is a "fiction".
NSW police in 2015 identified sovereign citizens as a potential terrorism threat in Australia.
