Darwin's lockdown has been extended by three days after the coronavirus outbreak in the territory grew to seven.
A man in his 50s linked to a gold mine is the latest case, Chief Minister Michael Gunner announced on Monday.
The man is a close contact of a previous case and was infectious in the community for 36 hours.
"I am really sorry about this," Mr Gunner said during a press conference.
"It is absolutely necessary ... the reality is we are not out of the woods yet. Not by a long way."
The lockdown, which was put in place for the Greater Darwin area, was originally in place for 48 hours beginning at 1pm on Sunday. It will now end at 1pm on Friday.
Territory Day events and fireworks, planned for July 1, will be postponed, Mr Gunner said.
The snap lockdown was announced after 900 workers left Newmont's Granites Mine about 540km northwest of Alice Springs, where a Victorian man had earlier tested positive.
About 400 fly-in, fly-out workers travelled in recent days to Brisbane, 250 flew to Perth and 29 headed to South Australia, with 244 remaining in the Top End.
"We are facing our biggest threat since the beginning of this crisis, we are still under threat and in the middle of the storm but we will come through it," Mr Gunner said.
"Everybody is doing what they need to be doing and we are looking out for each other. It will take a little longer than we hoped and hurt us a little more than we hoped but we will smash this thing, I know we will."
Exposure sites identified, visitors ordered to isolate
For the first time since the pandemic began, the territory will identify exposure sites.
Anyone who visited the Buff Club in Darwin on Friday, June 25 between 5.30pm and 8pm is directed to get a Covid test and self-isolate for 14 days.
Households of those visitors are also required to isolate.
Mr Gunner also listed two casual contact sites. Anyone who attended the following venues at the specified dates and times must immediately get tested and isolate until a negative result is received.
BWS, Parap, Friday June 25, 4pm - 4.10pm
Bunnings Darwin (Bagot Road), Saturday 26 June, 10am - 10.15am
Darwin Airport is considered a low exposure site after a mine worker arrived from Queensland. Anyone at the airport between 1.30pm and 3.35pm on Friday 25 June is advised to monitor for symptoms and isolate and get tested if symptoms develop.
Five reasons to leave home
Residents – not including those in isolation – are only permitted to leave home for one of five reasons:
To receive health care or attend medical appointments
To undertake shopping and get necessary goods and services
To exercise for up to one hour a day within 5km of your home and only with members of your household or one other person
To undertake essential work
In case of an emergency or if there is family violence or to provide essential care to a loved one or dependent
Masks are also mandatory when leaving home.
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