Some 3000 people who plan to march in a Sydney Invasion Day rally on Tuesday face fines and imprisonment, NSW's police minister has warned.
But rally organisers are hoping the NSW Supreme Court intervenes to approve their protest, despite Covid-19 public health orders limiting outdoor gatherings to 500 people.
It's a major flashpoint on an Australia Day unlike any that have come before.
The annual Invasion Day rally is scheduled to start at Sydney's Domain at 9am, with more than 3000 clicking 'attending' on the Facebook event on Monday evening. Almost 4000 more people said they were 'interested' in the event.
"Anyone who attends tomorrow will be exposed to fines and imprisonment because they'll be in breach of the public health orders," Police Minister David Elliott told 2GB on Monday.
Rally organisers are calling for Australia Day to be abolished and for justice for First Nations people.
Lawyers representing protest organisers were on Monday evening planning to approach the Supreme Court to give the gathering the green light.
Organisers earlier claimed that their attempts to work with the NSW government and police to agree on a Covid-safe approach had fallen on deaf ears.
Greens MP David Shoebridge published a letter sent to Health Minister Brad Hazzard requesting an exemption from public health orders for the rally, attaching a six-page safety plan, which includes compulsory masks and safety marshals.
But Mr Hazzard did not grant the exemption, and organisers say police and other government representatives have declined to meet with them.
Police have warned of a "highly visible and mobile ... operation" across the state to ensure Australia Day revellers comply with Covid restrictions.
Assistant Commissioner Mick Willing said police would focus on public safety, alcohol-related crime and anti-social behaviour.
He said police did not intend to disrupt any plans, but cautioned that they were empowered to make sure gatherings were not too big and people were wearing masks in mandated settings.
Circular Quay will be closed from 6pm, with only ticket holders, those with hospitality bookings, venue workers and residents allowed through barricades.
Road closures are also expected in the Sydney CBD.
Royal Australian Air Force aircraft will conduct a flypast over Sydney Harbour to celebrate the national public holiday. One or two F-35A Lighting II aircraft from Number 3 Squadron based at RAAF Base Williamtown will take part in the spectacle.
The day's events, both celebration and protest, will proceed in sweltering heat, as a cool change is only expected to break Sydney's heatwave on Tuesday evening.
Temperatures of over 40C may hit western Sydney, with coastal areas benefiting from a cooler sea breeze.
Marches to go ahead across Victoria
A number of events will go ahead in Victoria on Tuesday, headlined by a central Melbourne march that is expected to draw thousands of "Invasion Day" demonstrators.
Event organisers, Warriors of the Aboriginal Resistance, are demanding the abolition of Australia Day.
"There is nothing to celebrate on Australia Day," it said on Monday
"Aboriginal communities continue to be oppressed, policed, discriminated against and disenfranchised."
More than 3500 people have signalled their attendance on social media for the event, which will begin in front of Parliament House from 10.30am.
Attendees have been told to organise in groups of 100 and stay 10 metres apart, wear masks and bring hand sanitiser.
A Victorian NAIDOC-led Day of Mourning Dawn Service will also be held earlier in the day.
Victorian minister Melissa Horne said she understood January 26 was a difficult day for First Nations people and implored protesters to safely demonstrate.
Anti-lockdown protesters to also take to the streets
Anti-lockdown protesters have also pledged to march later in the day after repeatedly shunning health advice last year.
The group plans to meet at Queen Victoria Gardens and march from Park Pavilion to Catani Gardens near St Kilda Beach.
The "People's Australia Day Parade" will conclude with a "beach party" to "celebrate what's great", its organisers said on Facebook.
A Victoria Police spokeswoman told AAP it was aware of several planned demonstrations in the CBD and issued a stern warning to would-be troublemakers.
Premier Daniel Andrews is meanwhile scheduled to attend the annual flag-raising ceremony at Melbourne Town Hall on Tuesday morning.
He will be joined by Victoria's Governor Linda Dessau, who will later host a citizenship ceremony at Government House for 50 conferees from nations including Iraq, Fiji, Hungary, Vietnam, Pakistan and Colombia.
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