The World Health Organisation yesterday declared the new coronavirus variant to be "of concern" after it originated in South Africa.

Covid-19 Response Minister Chris Hipkins said from 11.59pm tomorrow, only New Zealand citizens will be allowed to travel here.

They will also be required to stay in managed isolation for a full 14 day period and undergo testing.

People already in transit will also need to go into MIQ.

The countries are: South Africa, Namibia, Zimbabwe, Botswana, Lesotho, Eswatini, Seychelles, Malawi and Mozambique.

Australia announced similar restrictions earlier today.

Hipkins said the decision follows a public health risk assessment and discussions with counterparts in Australia.

"It was important that the Ministry of Health rapidly and thoroughly assess all the latest information from overseas, as it always does when there is a new Covid-19 variant or research," Hipkins said.

Officials were confident the variant hadn't yet entered New Zealand as whole genome sequencing, which is undertaken routinely on all border-related cases, has shown all had the Delta variant, Hipkins said.

"New Zealand remains in a very good position to prevent this variant entering the country and deal with it if it does appear at our border. Our MIQ facilities and frequent testing of arrivals continue to serve us well.

"Given the evolving situation, a cautious approach is warranted. Adding these countries to the very high risk country register is an appropriate and proportionate measure as more evidence is gathered globally on the Omicron variant," Hipkins said.