Kiwis at sea on true coronavirus spread

New Zealand is on day five of a government-ordered lockdown.
New Zealand is on day five of a government-ordered lockdown.

The New Zealand government has conceded it needs to up COVID-19 testing rates to get a clearer picture of how the virus is spreading through the country.

Prime Minister Jacinda Ardern said New Zealand had the capacity to test at twice the current rates - around 1700 a day - and she expected doctors to hit those targets.

Ms Ardern's government's sluggishness to ramp up testing has drawn criticism from the opposition National party and comes after repeated calls from the World Health Organisation to up testing rates.

But the prime minister denied this was a concession of a mis-handled response to the growing pandemic.

"Clinicians make the decision (to test,) not politicians. The discretion has always been there," she said.

"I have continually sent a message and will keep doing so, to test, test, test."

Around two per cent of New Zealand's total of 647 cases have taken place through community transmission, evidence of an uncontained outbreak.

Ms Ardern's call to arms comes on the first day of a parliamentary select committee into the pandemic, in which a noted epidemiologist cast shade on the total number of cases in the community.

Otago University Professor Sir David Skegg told the committee that only rigorous testing would provide the answer.

"Have we got 500 undiagnosed cases out there or do we have several thousand? We don't know," he said.

Sir David also called on the government to follow Australia and mandatorily quarantine all international arrivals, rather than simply symptomatic ones.

New Zealand is on day five of a government-ordered lockdown with harsher restrictions on business and socialising than Australia.

Also on Tuesday, the Kiwi government finally released its government-commissioned modelling into the scale of the challenge facing their health system.

It revealed a worst-case scenario, without action, would have produced around 27,600 deaths, sent 146,000 to hospital and two thirds of the overall population contract the virus.

Those numbers prompted the prime minister to send New Zealand into lockdown last week, when nationwide cases sat at just 102.

Director-General of Health Ashley Bloomfield announced a fresh 58 cases on Tuesday to take the overall tally to 647.

Of those cases, 14 require hospital treatment with two people in intensive care but a stable condition.

The 58 new cases represents a small drop from previous days.

There were 76 new cases announced on Monday, 63 on Sunday, 83 on Saturday and 85 last Friday.

"While this is a drop in the number in the last day or two, I have no sense this is a drop overall," Dr Bloomfield said.

"Our full expectation is the number of cases will increase over the next seven to 10 days."

Australian Associated Press