The Northern Territory's daily COVID-19 case tally has jumped to 60 infections as Omicron starts spreading through the community.
From 6pm on Friday, people will be required to wear face masks in all indoor public areas, putting a dampener on New Year's Eve celebrations for many.
"In the past 72 hours there has been a growing trend of community transmission," Chief Minister Michael Gunner told reporters on Friday.
"We had one case of community transmission on Wednesday, four cases ... yesterday and we have at least 11 cases of community transmission today."
More than 30 of the new cases are infected interstate arrivals or people who were close contacts of previous cases.
Another six cases are linked to a regional Delta outbreak that continues to spread in Katherine, 320km south of Darwin, and Tennant Creek, 510km north of Alice Springs.
The status of another 15 cases is yet to be determined.
The majority of the community transmission is in Darwin.
"While we presume all regional cases are Delta we presume interstate arrivals and their close contacts are Omicron," Mr Gunner said.
The chief minister announced a mask mandate for all public indoor venues across the territory, to start at 6pm on Friday.
"I know the timing of the mandate is not ideal coming into New Year's Eve," Mr Gunner said.
"You can still go out. We want you to go out. We want you to have as much fun as you can but we need you to do this as safely as possible. Mask up."
