New Zealand will end a three-and-a-half-month lockdown in the country's largest city Auckland early next month as it adopts a new coronavirus control strategy, Prime Minister Jacinda Ardern said Monday.

Ardern said that from 11:59pm on December 2, New Zealand would adopt a new Covid-19 response -- first flagged last month -- that aims to contain the highly contagious Delta variant, rather than attempting to eliminate it completely.

"The hard truth is that Delta is here and not going away," she told reporters.

"While no country has been able to eliminate Delta completely, New Zealand is better positioned than most to tackle it." Ardern's coronavirus response until now has strived for "Covid Zero" elimination, with strict lockdowns, rigorous contact tracing and tight border controls.

While it has resulted in just 40 deaths in a population of five million, pressure had been building to end a lockdown in Auckland imposed in mid-August when Delta was first detected.

Ardern had initially planned to implement the new system when the vaccination rate in the country reached 90 percent, but set the December 2 opening-up date even though the level is currently around 83 percent.

Director-General of Health Ashley Bloomfield said he was comfortable with what amounts to the largest revamp of Covid-19 policy since the start of the pandemic.

"We're going into this next phase in, one could argue, the best possible position," he said.

"We've got a controlled outbreak, we're going into summer and we've got high and increasing vaccination rates." Under the new three-tier traffic light system, green has almost no virus controls, while red means businesses can remain open but customers must be vaccinated and observe social distancing.

"The key difference between the two systems is that vaccine passes will shortly be required at places like bars, gyms and restaurants," Ardern said.

She said Auckland would initially be placed under the red setting and officials were still determining how to classify other areas.

Auckland is currently sealed off from the rest of New Zealand, with roadblocks due to be removed on December 15.

Stringent quarantine rules for international arrivals will remain in place but Ardern has committed to easing them early next year.