New Zealand will go into level 4 lockdown from midnight tonight.

Jacinda Ardern has made the announcement following a positive Covid-19 case in Auckland today.

This afternoon the Ministry of Health revealed the new case, and said a link between the case and the border or managed isolation had not been established.

Health officials have been interviewing the case so contacts can be traced and any locations of interest identified.

A 58-year-old man from Devonport tested positive this afternoon.

It is not yet confirmed if it is the Delta variant, and genome sequencing is due back tomorrow morning.

The positive case visited the Coromandel over the weekend, and a number of places have been identified as locations of interest.

At this stage 23 have been in total. We will prodive an update when we can.

Aucklanders have been warned to maintain social distancing and take other precautionary measures.

People lined up outside Countdown in Greerton tonight. Supplied photo.

The development prompted people to line up outside testing centres, as well as supermarkets, across the city today.

In a media standup tonight, the Prime Minister says Auckland and the Coromandel will be in level 4 lockdown for seven days, while the rest of the country will be in lockdown for three days.

The Ministry of Health today says a link between the case and the border or managed isolation had not been established.

Health officials had been interviewing the case so contacts could be traced and any locations of interest identified.

This evening health officials released five locations of interest in the Coromandel, which has been published on the Ministry of Health website.

In announcing the government's decision Ardern said going hard and early had worked before and that the Delta variant was harder to combat.

Bloomfield said they were assuming it is the Delta variant. The man, a 58-year-old male from Devonport, on Auckland's North Shore, lives with his wife.

She was tested yesterday and returned a negative test.

Bloomfield thanked the person who tested positive for going for a test and emphasised although he wasn't vaccinated, he had booked in to get his jabs.

Ardern said it was not a matter of if but when the variant arrived in the community.

"I want to assure New Zealand that we have planned for that eventuality and that we will now be putting in place that plan to contain and stamp out Covid-19 once again," Ardern said.

"Going hard and early has worked for us before, while we know that Delta is a more dangerous enemy to combat the same actions that overcame the virus last year can be applied to beat it again."

The couple visited Coromandel last week, Bloomfield says. They returned on 15 August.

The man is a frequent user of the Covid-19 tracer app.

Locations of interest have been identified in both Coromandel and in Auckland.

Five locations of interest in Coromandel

The contact tracing locations of interest include Star and Garter Hotel, Umu Cafe, BP Gas Station on Tiki Rd and Taras Beads. The man visited them between 13 and 15 August.

Further locations between Coromandel and Auckland are likely to be identified.

Bloomfield says he wants to assure New Zealanders health officials acted swiftly and are taking immediate actions.

There will be additional testing centres in Auckland tommorrow and all district health boards will ensure there is efficient testing capacity.

Last wastewater testing on North Shore on 11 August has returned negative results.

"This case was identified in Auckland but it is a national issue," Bloomfield said.

New Zealand was one of the last countries to experience a case of Delta, Ardern said.

It is a "game changer" and the country only had one chance to get on top of it, she added.

It will be for three days for all of New Zealand but for seven days for Auckland Coromandel, Ardern said.

"We have made decisions on the basis it is better to start high then go down levels," she says.

We have seen the consequences of not acting quickly enough, she added.

The underlying principal of level 4 was to reduce contact to a bare minimum, Ardern said.

"Beating Delta means lifting our game.

"I ask New Zealanders to please follow the rules to the letter."

People must stay at home in level 4, only leaving for essential services, she said. "And if you undertake these activities, please wear a mask when you leave your house."

Stay 2m away from anyone you pass, don't congregate and don't stop to talk to your neighbours, she said.

"We know from evidence overseas, that the delta variant can spread just by walking past someone.

"If you are completely isolated or live alone, remember you can join a bubble with one other person...it must just be one other person though."

More to come...

*See all SunLive's COVID-19 news