Police Commissioner Jamie Chalker said major crime would undertake an investigation into whether somebody breaching the directions of the Chief Health Officer had ultimately led to the death of the woman in her 70s who died on Thursday night.

"Unfortunately, this death does apparently have links to a breach...It appeared to be the seed that started the spread of COVID within the Northern Territory and as such major crime are now undertaking an investigation," he said.

Commissioner Chalker said the investigation would see if there was "any criminality" involved in the events that led to her death.

"The death has occurred in the Northern Territory, linked to COVID. COVID had not previously been in the Northern Territory in an environment where it couldn't be contained," he said.

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"We will now investigate to identify what the causation may have been that ultimately led to COVID being contracted by the lady who passed away last night and whether there's any criminality in relation to that."

Commissioner Chalker declined to comment further because the investigation was ongoing.

The latest outbreak in the NT started when an infected woman illegally entered the NT in late October.

The 21-year-old lied on her border entry form before travelling from Cairns to Darwin after visiting Victoria, where she contracted the virus.

She infected a man in Darwin before the virus spread to Katherine, then the Aboriginal communities of Robinson River - 1000km southeast of Darwin - Binjari and Lajamanu.

Meanwhile, two travellers to the NT from Victoria and South Australia - unrelated to the current cluster - have tested positive for the virus.

They have been moved into the Howard Springs quarantine facility with their families.

Across the NT, 88 per cent of people over the age of 16 have had their first vaccine dose and 78 per cent are fully vaccinated.

-with Australian Associated Press