Prime Minister Jacinda Ardern has announced New Zealand, outside of Auckland, will move to alert level 2 from 11.59pm Tuesday 7 September. Meanwhile, Delta alert level 2 looks different and settings have been changed.

Bloomfield says essential workers crossing alert level boundaries will be required to undergo weekly testing.

Those people will be expected to have had a test in the last seven days and must show proof of it, he says.

Three thousand people are crossing the border between Auckland and the rest of the country each day.

People who transit between Auckland will need to come through without stopping if they're moving from south of Auckland to Northland.

Face coverings are now mandatory at level 2 in most public venues, Ardern says.

You can take your mask off in venues like restaurants and cafes, she says.

Staff at public facing businesses in level 2 must wear face coverings.

"To keep it really simple, if you're out at about at indoor venues, please wear a mask," Ardern says.

Only five of the 20 new cases reported today were infectious while in the community, and all new cases were in Auckland.

No cases linked to the current outbreak have so far been detected outside Auckland or Wellington, with the last case in the capital reported on Friday.

Public health experts have however warned that if the country does move to level 2, it would be with tighter restrictions than previously such as mask wearing and record keeping requirements.