WELLINGTON • It took just eight days for New Zealand to lose its Covid-free status when two women, who had been given permission to leave quarantine early upon arriving from abroad, tested positive for the coronavirus, the authorities said yesterday.

Prime Minister Jacinda Ardern, who has enjoyed enormous popularity for her success in ridding the country of coronavirus infection, said the government would review what happened, but added that it was clear that checks were not adequate in this case.

"Vigorous testing is now taking place across those who were in the quarantine facility at the same time and those who may have had any, even the remotest, chance of contact (with the women)," Ms Ardern said in a Facebook Live post.

New Zealand had trumpeted its achievement last week of becoming one of the first countries in the world to eliminate Covid-19 and return to pre-pandemic normalcy, lifting all social and economic restrictions except border controls.

The country's borders are open only to returning Kiwis and their families, other than some exceptions for business reasons and on compassionate grounds.

It requires all people arriving from abroad to quarantine for 14 days to avoid reintroducing the disease.

The two women, who are in their 30s and 40s, had travelled from Britain to visit a dying parent in Wellington on June 7, director-general of health Ashley Bloomfield said in a news conference.

Both had gone into quarantine in Auckland after landing but had been given special permission to leave on compassionate grounds, even though one had symptoms which she attributed to a pre-existing condition.

They tested positive after arriving in Wellington and were in isolation, along with the only relative they had contact with in the capital.

Officials immediately began tracking anyone who had come into contact with the women.

Mr Bloomfield said he was not afraid that the cases could lead to a fresh outbreak because systems were in place to trace their movements.

"A new case is something we hoped we wouldn't get, but it's also something we expected and have planned for," he told reporters.

The new cases ended a 24-day streak of no new infections in the country.

Health Minister David Clark said he was suspending all exemptions to the quarantine rules until he had confidence in the system.

"Compassionate exemptions should be rare and rigorous and it appears that this case did not include the checks we expected to be happening. That's not acceptable."

One family member of the women has been isolated in Wellington.

Staff at the hotel where the women stayed would be tested. Co-passengers on their flight, staff at Auckland airport and anyone else whom the women met would be contacted.

The cases take the total number recorded in the country to 1,506. Deaths from the disease remain at 22, among the lowest in the developed world.

New Zealand's five million people emerged from the pandemic while big economies such as Brazil, Britain, India and the United States continue to grapple with spread of the virus.

This was largely due to strict restrictions in which most businesses were shut and everyone except essential workers had to stay home.

Ms Ardern has been wary of saying the country was "Covid-free" as the global pandemic raged around the world and new cases were likely to come to the country.

She said earlier this week: "I don't want New Zealanders to believe that the battle is over when it is not."

REUTERS, AGENCE FRANCE-PRESSE