There have been 13 new cases of coronavirus in New Zealand in the last 24 hours and the health ministry says community transmission of the virus may now be in New Zealand.

Director-general of health Dr Ashley Bloomfield said the 13 new cases were spread across four cases in Wellington, three in Auckland, one in Waikato, one in Taranaki, one in Manawatū, and one in Taupō. There is one case in Nelson and one in Marlborough.

It brings New Zealand's total to 52 confirmed cases, with a further four probable cases. Originally, the ministry said there were 14 new cases, however this was later revised down to 13.

Bloomfield confirmed the new figures at his Saturday morning press conference in Wellington.

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ABIGAIL DOUGHERTY/STUFF People are still out and about in the streets of Auckland City despite coronavirus numbers rising.

In two instances, no link to overseas travel had been found, Bloomfield said.

The ministry could not rule out the risk of community transmission regarding those cases, Bloomfield said.

"We always knew that cases apparently not linked to travel would happen and we are prepared for that," Bloomfield said.

It was "more important than ever" individuals were tracked and traced, so they could get into self-isolation and contain further spread.

There were 1500 tests for Covid-19 done on Friday, up from 1000 on Thursday.

Three of the confirmed cases were being treated in hospitals. Of those, one was in Nelson, one was in Queenstown and one was in North Shore Hospital in Auckland.

STACY SQUIRES/STUFF Director-general of health Dr Ashley Bloomfield said he couldn't rule out community transmission of the virus on Saturday.

Of the two cases that are possible community transmission, one is in Auckland and one is in greater Wellington.

In the Auckland case, the partner of the person has had close contact with people who travelled overseas. That person's partner was being tested to see if they were the transmitter.

The Wairarapa case had no obvious link to overseas travel.

That person was symptomatic, which was why he was tested. The ministry would not say where in the Wairarapa the person was located.

Bloomfield hoped the testing levels the ministry was undertaking would give the ministry an idea of whether or not the country had community transmission.

The levels of testing were relative to what was being done in South Korea, he said.

CRUISE SHIPS

Meanwhile, New Zealanders on the Ruby Princess cruise ship that docked in Sydney after touring New Zealand were now being considered close contacts.

Three Australian passengers and one crew member on board had tested positive for coronavirus.

Fifty-six New Zealanders who were on board the ship, including 28 who have already returned to New Zealand, were being contacted by the health ministry.

These people would be covered by the requirement since March 15 for all travellers returning to New Zealand to go into self-isolation for 14 days.

When the Ruby Princess docked in Wellington there were five people who had flu symptoms, Bloomfield said. They were tested, and the results came back negative.

So, while there have now been three positive cases of coronavirus on the ship, they weren't those people who were tested in Wellington.

Details on the movement of both the Ruby Princess ship and the Celebrity Solstice ship, which had a confirmed case of coronavirus involving a New Zealander, were available on the health ministry's website, Bloomfield said.