Health Minister Natasha Fyles said the virus has spread to every region in the territory as the number of active cases grows to 1200.

"It is concerning that we have had significant escalation in the numbers but we expected this," she told reporters on Friday.

"We can still manage these numbers that we're seeing and I expect these numbers to grow over the coming days."

Locally acquired infections almost doubled in the past 24-hour reporting period to 70 cases and another 191 remain under investigation.

Another 80 infections are known close contacts, 71 cases are interstate arrivals, and 68 per cent are aged between 20 and 40.

Meanwhile, an investigation is under way into cases in Nhulunbuy in east Arnhem Land, about 700km east of Darwin.

More than 20 infections were also detected in Alice Springs and one was detected in Tennant Creek, 510km to the north.

There are five virus patients in NT hospitals. Two are in intensive care and one is ventilated.

"I know today's case numbers are high, but it's not a surprise," Ms Fyles said.

"The reassuring part to us is around the hospitalisations."

A territory-wide lockout of unvaccinated people aged 16 and over started on Thursday and will continue until midday on Monday when a proof of vaccination pass system will be rolled out.

It will run on the territory's check-in app and apply to most hospitality and entertainment venues.

Under the lockout, unvaccinated people can only leave their homes for medical treatment and testing, essential goods and services, and to care for a vulnerable person.

They are not permitted to go to workplaces or travel more than 30 kilometres.

The territory recorded 256 new cases on Thursday with 38 locally acquired, which was a record and more than double Wednesday's tally of 117 cases.

Australian Associated Press