New Zealand could be kept in lockdown until October after another 13 cases linked to a family-of-four were uncovered.
Health authorities are scrambling to contain the growing cluster of cases linked to the Auckland family, who tested positive on Tuesday, plunging the country back into lockdown.
There was early speculation the virus arrived on the packaging of frozen-food shipments before infecting a family member - a worker at Americold - who unpacked them.
The unexpected outbreak plunged New Zealand back into lockdown after 102 days without recording a locally transmitted case of the virus.
Chinese health authorities have now revealed that traces of coronavirus have been found in frozen chicken wings and on food packaging.
A sample taken from frozen chicken wings that had arrived in Shenzhen from Brazil were reportedly contaminated with COVID-19, with an epidemiologist now warning the public to take precautions around frozen food.
Health authorities are scrambling to contain the growing cluster of cases linked to the Auckland family (pictured: Prime Minister Jacinda Ardern on Thursday)
The new cases include five children, including one toddler (pictured, cars queue at a COVID-19 test centre in Auckland on Thursday)
Frozen shrimp from Ecuador sold in Xian also tested positive for coronavirus, according to local authorities, with the virus able to survive cold temperatures.
This means that an infected worker at a frozen food storage facility could transmit the virus to unknowing shoppers, as the food is dished out to supermarkets across the country.
The new cases include three men in their 50s, two men in their 40s, a man in his 30s, a woman in her 60s, a woman in her 50s, two girls, one boy and a teenage boy, taking the total in the cluster to 17 cases.
This includes a little girl aged between one and four, and a boy aged between five and nine.
Another case is a girl aged between 10 and 14, and a boy between 15 and 19 - as well as a pupil at Glamogran School.
None have recently travelled overseas.
Despite fears the family member, who works at a cold store facility, contracted the virus from imported food, Deputy Prime Minister Winston Peters suggested the cluster may be linked to a hotel quarantine breach.
Mr Peters said he hasn’t been officially informed that there was a breach but expects it to be announced by health officials on Friday.
He said his source was a 'very reliable' journalist investigating the outbreak.
Chinese health authorities have revealed that traces of coronavirus in imported frozen chicken wings and on food packaging have been found (pictured, a lab in China on Wednesday)
Epidemiologist Michael Baker said New Zealand could remain in lockdown for another seven weeks (pictured, Wellington on Wednesday as the country went back into lockdown)
'It wasn't an official, I found out from somewhere else, but I think there's been a breach inside our quarantine system,' he told the ABC on Thursday.
The unexpected outbreak has prompted warnings from a top scientist that New Zealand could remain in lockdown for another seven weeks - the start of October.
Epidemiologist Michael Baker said it will depend on how far the outbreak had already spread and if a direct link to an overseas case could be identified.
'You would expect a longer lockdown would be more likely. The most positive outcome is if contact tracing identifies a clear line of transmission from an imported case or someone working at managed quarantine,' Prof Baker told the NZ Herald.
'If the direct line to imported cases is established quickly that's very helpful and then it's finding out the extent of infection among the contacts, if some of them are infected then it's working out the extent of infection among their contacts and so it goes on.'
Prof Baker suggested New Zealand would go back to the situation in March when no more cases were recorded after five weeks of Level Four restrictions and then two weeks at Level Three.
All the 600 families and staff at Glamorgan School in Torbay have been ordered to stay in self-isolation after a boy tested positive
Prof Baker suggested New Zealand would go back to the situation in March when no more cases were recorded after five weeks of Level Four restrictions and then two weeks at Level Three
'I don't think anyone is imagining that will be necessary this time around but if you are taking the extreme range of possibilities we know from experience in March that it was very effective,' he said.
Meanwhile a school in Auckland's north shore has been closed after a young student tested positive to the virus.
All the 600 families and staff at Glamorgan School in Torbay have been ordered to stay in self-isolation.
Health officials are working to trace close contacts of the child, including classmates and staff.
The school is set to reopen on Monday, but authorities have warned it could remain shut next week if more cases are confirmed there.
A six-year-old boy at Southern Cross Campus in Auckland has also tested positive to coronavirus.
The school's board held an emergency meeting on Thursday night. Two teachers and 28 of the boy's classmates are now in self-isolation.