New Zealand will lift a Covid-19 lockdown on nearly two million people on Sunday, as authorities say they are confident that a virus cluster in the country's largest city has been contained.

Prime Minister Jacinda Ardern said Friday the stay-at-home order for Auckland will end early Sunday, one week after it was imposed in response to a mystery case that contact tracing could not explain.

It later emerged that family members of the infected person had defied isolation orders, socialising with friends who later tested positive for Covid-19.

With the case's origins solved, quarantine protocols were enforced and Ardern said the cluster had been limited to 15 cases, allowing Aucklanders to leave their homes.

"This plan is consistent with our cautious and careful elimination strategy," she told reporters.

New Zealand has won widespread praise for its coronavirus response, recording just 26 deaths in a population of five million.

Ardern acknowledged Aucklanders, who have endured two lockdowns in the past month, were weary but urged them to stick to rules designed to curb the spread of the virus.

New Zealand will soon lift a Covid-19 lockdown on nearly two million people after a cluster of cases in Auckland was contained
New Zealand will soon lift a Covid-19 lockdown on nearly two million people after a cluster of cases in Auckland was contained AFP / DAVID ROWLAND

"We may not be in the devastating position that much of the world finds itself in but the elimination strategy can still feel like hard work," Ardern said.

"It's completely natural to feel fatigued, Covid is hard work for everyone.

"Thank you for pushing through once again, we're confident we'll once again get ourselves back to a position where we have the freedoms New Zealanders have so enjoyed."

Although lockdown will end on Sunday, Auckland will continue to restrict numbers at public gatherings to 100 and require face masks on public transport.

The rest of New Zealand will move to the least restrictive setting in the country's Covid-19 response system.

New Zealand Cricket welcomed the move, which will allow unrestricted crowds at the fifth and final Twenty20 international between the Black Caps and Australia in Wellington on Sunday.

America's Cup organisers said the yachting regatta would begin in Auckland on Wednesday despite the city's restrictions on spectator numbers.

The showdown between Team New Zealand and Luna Rossa of Italy had been scheduled to being this weekend but was delayed by the lockdown.

Coronavirus