Darwin, Palmerston and Litchfield will go into a full lockdown for 48 hours after there were four new cases linked to the Northern Territory mine cluster.
From 1pm local time on Sunday, there will only be five acceptable reasons for leaving the home: medical treatment, including COVID-19 testing or vaccination; shopping for essential goods; essential work; one hour of exercise per day, no more than five kilometres from your home; and to provide care or support to a family member who cannot provide support for themselves.
Chief Minister Michael Gunner said it’s believed the new local cases are of the highly-infectious Delta variant.
"We are assuming the worst," he told reporters.
"We are expecting more cases. There is a stronger chance that any new cases will have exposure sites, which makes the job of tracing and testing much bigger."
"This is not something we ever wanted to happen here," he went on. "But we have always planned and prepared for the chance that it could happen. We have tested this scenario over and over again and we will do the hard things now to stay safe."
On the decision to impose a lockdown, he said: "We know how infectious this can be. One case turns to two, two into four, we know what happens. I would rather regret us going too hard too early, than go too easy and risk it all.”
The man, who tested positive on Friday, arrived in the territory on 18 June.
He was asymptomatic and only discovered the infection when he was alerted to a potential hotel quarantine breach in Queensland through a message from interstate authorities.
The man had travelled from Bendigo via Brisbane, where he was ordered into a quarantine hotel on 17 June.
He was in quarantine for a single day, but is believed to have caught the virus there. He is thought to have been unknowingly infectious from 18 June when he travelled to the Granites Mine in central Australia, 540km northwest of Alice Springs.
His diagnosis forced the mine to shut down on Saturday and 754 workers to isolate on-site. A further 900 people, who have since flown to Darwin, Alice Springs, Perth and Brisbane, have also been ordered to isolate at their homes.
Health Minister Greg Hunt said there will be a focus on protecting remote Indigenous communities in the Northern Territory following the outbreak.
"The Northern Territory is responding magnificently, as is New South Wales," he told reporters on Sunday.
"But our primary concern, on the advice that I have from Paul Kelly and Professor Brendan Murphy, is to ensure that everything that can be done to protect remote Indigenous communities in the Northern Territory."
Mr Gunner said one of the new cases has travelled to NSW, with NSW Health assuring the public on Sunday the man was isolating in the Hunter New England region and had not been in the community while infectious.
The NT premier said there were two new positive cases from the cohort currently isolating on the mine in the Tanami.
“They are being evacuated to the centre of a national resilience," he said.
“We received confirmation this morning that one of the mineworkers identified as a close contact who lives in Palmerston has tested positive to COVID-19 while in the Centre for National Resilience.”
There are also concerns the man's infection could see the virus spread to the territory's many remote communities.
Australia's Deputy Chief Medical Officer, Professor Michael Kidd, said on Saturday federal authorities had plans in place should the virus spread in Indigenous communities.
"Right from the start of the pandemic we've had plans in place to work with local Aboriginal communities to respond to outbreaks in remote areas in Australia," he said.
"The Commonwealth is working with the Northern Territory government and the Aboriginal community controlled health services in the affected area to provide whatever support is needed."
With AAP
