Prime Minister Jacinda Ardern has gone into self-isolation after coming into close contact with a positive COVID-19 case.

"The Prime Minister is asymptomatic and is feeling well. In line with Ministry of Health advice she will be tested immediately tomorrow and will isolate until Tuesday," a spokesperson says.

The Prime Minister and Governor-General Dame Cindy Kiro had been in Northland prerecording at the Waitangi Treaty Grounds for the Waitangi Day broadcast next weekend.

They were exposed during flight NZ8273 from Kerikeri to Auckland on Saturday January 22. The flight was added to the Ministry of Health website as a location of interest this evening.

Whole-genome sequencing is expected to show the case has been infected with the Omicron variant.

All other passengers on board NZ8273 are also close contacts and need to self-isolate, get tested immediately and remain in isolation for 10 days following their exposure. They will also need to follow further requirements from public health officials.