There are no new cases of Covid-19 in the community in New Zealand today.

There are two cases in MIQ.

Almost 100 port workers, meanwhile, face an anxious wait for test results after a container ship off the coast of Tauranga recorded positive cases among the crew.

Testing at Port of Tauranga is under way for workers who had contact with the container ship Rio De La Plata, now identified as having a number of Covid-positive crew onboard.

Testing of the crew of the container ship, currently at sea off the coast of Tauranga, has returned positive results for 11 of the 21 crew on board, with one test result currently indeterminant, said the ministry.

Health officials had worked with employers to identify 94 port workers who had contact with the ship, unloading cargo in shifts over the four-day period it was berthed at Port of Tauranga from 6pm on Wednesday August 4 to 2pm on Saturday, August 7.

All had been contacted, told to isolate awaiting a negative Covid test result, and are being tested today.

As of 11.30am today, 91 workers have been tested. The first results are expected later today.

"Some workers will require a second test, based on their contact with the ship, and will be required to remain in isolation until the result of those second tests are known," said the ministry.

According to local public health staff all infection prevention controls, and PPE protocol, were followed by port workers who had contact with the ship during their duties, said the ministry.

Four of Saturday's isolating cases, which had been reported without their travel history, could now be confirmed as having flown from Malaysia via Singapore en route to Aotearoa.

The Mattina vessel, in quarantine in Bluff, still has 13 of its 21 crew onboard.

Five mariners were released from MIQ on Saturday after two weeks of isolation, repeatedly recording negative Covid tests.

Two further mariners have been discharged from hospital and are understood to be recovering well in Southern DHB-arranged accommodation.

The final mariner off the ship is in a Christchurch MIQ facility.

Contact tracing staff have identified 2995 people who were required to isolate until a negative day 3 test after returning from the Australian state of Victoria between July 25-30.

Of those, 2848 have returned a negative test, six have returned overseas, and 91 have been granted a clinical exemption. The Ministry of Health spokesperson said the remaining 50 people who hadn't provided a negative test posed a "low risk" and no further action was necessary at this stage.

The Ministry of Health announced the Rio De La Plata Covid cases in a surprise media release just after 8am.

It said test swabs from the crew on the container ship, named as the Rio de la Plata, were taken in Tauranga as part of the requirement for the vessel to enter its next stop in Napier.

"The ship is linked to a Covid case in an Australian pilot who was onboard the vessel [in] July, in Queensland, and who later developed symptoms and then tested positive for Covid-19 nine days after being aboard the vessel."

That pilot was later identified as carrying the dangerous Delta variant of Covid-19 and had not been linked to any other cases in Queensland.

"Initial concerns about the link with the Australian pilot did result in loading of the vessel being temporarily halted on Wednesday (August 4) in Tauranga," the ministry said.

"An assessment carried out that day cleared the ship and unloading was allowed to resume the following day."

Almost 100 Port of Tauranga workers stood down

Although the crew - none of whom are said to be reporting any Covid symptoms, despite the positive results - went port-side in Tauranga, a total of 94 port workers who spent time on the vessel have now been stood down as they are asked to get a Covid test.

They will be stood down until a negative result is returned, a statement said.

"Testing for those staff is being arranged at the port this morning."

Confirmation of Covid-19 on board the Singapore-flagged container ship comes after three other overseas vessels were confirmed to have Covid outbreaks as they travelled through New Zealand waters in recent months.

The latest ship affected by the virus was the Mattina, in Bluff, which reported positive cases on board last month.

The Rio De La Plata container ship has been struck by Covid-19. Photo / Bernard Spragg

A few weeks before that, Spanish-flagged vessels the Viking Bay and then the Playa Zahara were also struck by Covid-19.

There remain no cases of Covid within the community anywhere in New Zealand, as of yesterday's Ministry of Health update.

Five positive cases were, however, identified in managed isolation facilities in Auckland.

The first traveller arrived on a flight from Malaysia, via Singapore, and tested positive on day 0 of their routine testing regime.

The other four positive cases are all travelling in the same bubble and tested positive on day 1 of routine testing.

Their full travel history is yet to be obtained, the ministry said. However, officials confirmed their flight came via Singapore as well.

A historical Covid case was also announced yesterday. The person arrived in New Zealand on November 26 last year, and came on a direct flight from the US.

They completed their managed isolation and quarantine period, it was confirmed.

Since January 1, there have now been 114 historical cases out of 712 cases.

New Zealand's official number of active Covid cases, as of yesterday, is 32.

A total of 2530 cases have been confirmed.