The prime minister has confirmed that the New Zealand border will be closed to anyone who is not a New Zealand citizen or permanent resident from 11.59pm on Thursday night.
Children and partners of New Zealand citizens and permanent residents will be allowed to enter.
People from the Pacific will be included in the border closure, as will temporary workers or temporary visa holders such as students.
"I recognise how extraordinary this is," said Ardern, but the measure had to be taken to protect New Zealand from Covid-19
"In no time in New Zealand's history has a power like this been used."
The ban applies to people not product, and those staffing freight ships and planes are not included.
Those who have travelled here from other countries recently are still required to self-isolate, and those who have been here longer are being encouraged to look at how they can get home.
"I'm not willing to take risks here," Ardern said.
