The Rio de la Plata container ship will not be granted permission to dock in Napier until all crew onboard the vessel have had negative results for Covid-19.
Of the 21 crew on the ship, 11 have returned positive results.
The ship, which was berthed at the Port of Tauranga for four days, is now anchored off the coast and where it will go will be decided this week.
It was supposed to head to Napier, but a Napier Port spokesperson said its border protocol meant the vessel was not allowed to berth.
Once negative tests are returned, the ship would be allowed to berth.
The spokesperson said the port's main priority was keeping everyone at the port and in the community safe.
They said all Napier Port staff were vaccinated against Covid-19, but that it did not account for Customs staff or stevedores.
More than 90 workers at Tauranga Port were originally stood down and told to get tested after spending time on Rio de La Plata.
The crew members were eventually tested but only because of entry requirements for Napier. Those tests revealed 11 of those onboard were positive.
Union for pilots, deck officers and masters Merchant Service Guild vice president Captain Iain Macleod said all crew coming to New Zealand should be tested.
The "should be tested on arrival," he told Checkpoint.
"It can be done with a bit of planning. You can at people out there, test them while they're at anchor.
"At the moment there's nine ships off Tauranga at anchorage, won't take much to get somebody out there with some swabs and test them."
He said before Rio de la Plata arrived in New Zealand, the ship had been through Malaysia, Singapore and Sydney.
"I think Customs are probably the most responsible ones to deal with because they have the overview and because the way the health response is segmented down to the DHB ... you've got DHBs around the country, one port officer doesn't talk to the other one."
He said when ships arrive in the country, their companies must declare that crew were clear of any disease.