The Northern Territory has extended its lockdown to Alice Springs after a central Australian mine worker infected four mates with COVID-19.

The worker left Newmont’s Granites Mine on Friday and spent seven hours at Alice Springs airport before flying to South Australia.

Four of his five Adelaide housemates have since been diagnosed with the virus and he’s developed symptoms, NT Chief Minister Michael Gunner said.

“Like all our other decision we will not take a punt on this,” he said on Wednesday.

“We will operate on the assumption that he has COVID-19 and we will operate on the assumption he was infectious while in the territory.”

Alice Springs will lockdown for 72 hours from 1pm Wednesday.

The lockdown direction applies to everyone inside the Alice Springs town council boundary, including hundreds of vulnerable Indigenous Australians who live in town camps.

“We are still in a dangerous period, The territory is still under threat,” Mr Gunner said.

It comes as no new COVID-19 cases were found in the Top End overnight.

The crisis started on Saturday when a young Victorian man, who travelled to the mine on June 18 via a Brisbane quarantine hotel, tested positive for the virus.

There are now 11 cases linked to the mine but only 10 have been recognised by the NT government.

An infected close contact of one of two mineworkers diagnosed in Queensland hasn’t been included in the Tanami Desert cluster.

Two other infected miners were also located at the site and evacuated to the Howard Springs facility.

Another mineworker, who’d travelled to NSW, was tested and found to be positive for the virus, as were two co-workers who’d travelled to Queensland, along with a close contact of one of them.

A Darwin man in his 50s, who left the mine on Friday, was also found to be positive for the virus.

He travelled to multiple venues, including Darwin’s infamous members-only watering hole, the Buff Club, for more than four hours, before being ordered into quarantine.

The most recent cases are the family of a mine worker who tested positive for the virus while in quarantine at the Howard Springs facility.

The Greater Darwin area is already in lockdown.

-AAP