Prime Minister Jacinda Ardern is encouraging Aucklanders to use face masks to visit places operating at Covid-19 Alert Level 3.
Ms Ardern said they were not mandating the use of masks "at this stage" but are actively encouraging their use in Auckland.
The Covid-19 website has been updated to encourage Aucklanders to wear masks when they are "out and about" and on public transport, and for the rest of the country under Alert Level 2 to "wear masks in situations where physical distancing is not possible, like on public transport or in shops".
Masks have only been mandated on flights from Auckland.
It comes as Auckland moves into Alert Level 3 and the rest of the country to Alert Level 2 at noon today until midnight Friday.
It was spurred by four new Covid-19 cases from a South Auckland family acquired through community transmission.
Healthline has received more than 2000 calls since late yesterday, Ms Ardern said.
The decision on what Alert Level the country and Auckland will go to or stay at from midnight Friday will be given with notice, Ms Ardern said, but would not put a timeline on it.
Surface testing is also underway in an Auckland cool store where a man from the family who've contracted the virus worked. Dr Bloomfield said they were doing environmental testing.
"We do know from studies overseas that actually the virus can survive in refrigerated environments for quite some time."