A person who flew from Auckland to Sydney this month has tested positive for Covid-19.
Air New Zealand flight NZ103 touched down in the Australian city on July 6 and has since been reported by New South Wales health officials as having a confirmed case of coronavirus on board.
The NSW Health website lists several seat rows as being close contacts of the confirmed case.
The case had led New Zealand health officials to now test household and other contacts of the passenger here in Auckland.
A ministry spokeswoman said health officials in New Zealand had also made contact with the passenger, media outlet Stuff reported.
"At this point, it appears the person may have been a previously unconfirmed case from March and this is responsible for the positive test result," she said.
"We will continue to fully investigate the circumstances of this positive result, including travel history."
Similar to New Zealand, all international travellers arriving in Australia must self-isolate for 14 days.
Stuff also reported a NSW Health spokeswoman as saying the passenger would have gone into quarantine where they would be offered optional Covid-19 tests on day 2 and day 10 of their stays.
It comes after a 22-year-old Korean man's recent positive Covid-19 test led local New Zealand officials to trace his movements and test close contacts.
The man had been living in New Zealand and travelled in Auckland and the South Island before leaving the country on July 21.
He subsequently tested positive to Covid-19 in South Korea.