A person who travelled from Auckland to Sydney early last month has tested positive for Covid-19, the Ministry of Health has confirmed.
"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," a spokesperson told 1 NEWS in a statement.
"We will continue to fully investigate the circumstances of this positive result, including travel history."
The person is believed to have been on flight Air New Zealand flight NZ103 from Auckland to Sydney on July 6. Close contact rows include 22, 23, 24, 25 and 26, according to NSW Public Health.
It's not clear when the person tested positive for Covid-19.
Ministry of Health says it was informed of the positive case by Australian health officials.
Auckland Regional Public Health is now following up with household contacts of the person in Auckland, along with other contacts "as appropriate".
Close contacts of the positive case have undergone testing and self-isolation, the Ministry of Health says.