Jacinda Ardern has called in a defence force chief to run New Zealand's COVID-19 quarantine system after losing confidence in her health department.
Ms Ardern lamented an "unacceptable failure of the system" on Wednesday as two Kiwis were allowed to leave their mandatory isolation without being tested for coronavirus, and later testing positive.
"It should not have happened and it cannot be repeated," Ms Ardern said sternly.
The two citizens were granted a compassionate exemption to their quarantine after returning from the UK in the hope of visiting an ill relative, who unfortunately died before they were able to be reunited.
The Kiwis are now in self-isolation along with a third family member in Wellington.
The breach has forced the health department to contact trace 320 people who may have been exposed to the virus, including passengers on a flight from Brisbane to Auckland on June 6.
"We are getting them all tested and isolated until a negative result is received," Director-General of Health Ashley Bloomfield said.
The two positive tests ended a 24-day run without new cases and cost New Zealand its COVID-free status, sparking a blame game between the government, opposition and health department.
Ms Ardern responded by tapping assistant chief of defence Air Commodore Darryn Webb to oversee the country's quarantine system.
"It is totally unacceptable that procedures we were advised were in place were not. Our job is now to fix that and that is exactly what I intend to do," she said.
Ms Ardern has also paused compassionate exemptions "until such time as we can guarantee a disciplined and rigorous system at the border that ministers have confidence in".
Citizens are allowed to return to New Zealand during the pandemic but are required to quarantine for a fortnight.
Protocols require testing for COVID-19 on day three and 12 of their isolation, however it is now unclear whether this is taking place.
Dr Bloomfield has taken responsibility for the blunder but has not offered an apology.
The opposition has renewed calls on hapless Health Minister David Clark to resign but he has refused.
"Ministers were clearly under the understanding that this was not going to happen, that people would be tested," he said.
"The Director General of Health has owned this failing ... I want assurances that this will never happen again.
"This is critical to New Zealand maintaining the status that is the envy of the world."
Mr Clark was previously caught bike-riding and bushwalking in contravention of lockdown rules.
In brighter news, New Zealand recorded no new cases of COVID-19 on Wednesday.