Four people from a cruise ship which docked in Sydney after travelling from New Zealand have tested positive for COVID-19.
The Ministry of Health is in the process of contacting the 56 New Zealanders who were on board the Ruby Princess.
One crew member and three passengers contracted the virus.
The Ministry of Health says any passengers on the cruise who have since returned to New Zealand would need to self-isolate for 14 days.
The ship travelled to Fiordland Dunedin Akaroa Wellington and Napier. The cruise was shortened after visiting Napier, for weather reasons, and the ship returned directly to Sydney and passengers disembarked on 18 March.
Passengers are not allowed to disembark the ship if they are unwell or showing signs of illness when it docks.
While the ship was in Wellington a small number of passengers had flu-like symptoms.
"These people never left the ship in Wellington. The results from those tests were negative," said the Ministry of Health in a statement on Friday.
One of the New Zealander's who tested positive for COVID-19 on Friday had been on a separate cruise around the country.
The Auckland man in his 60s joined the Celebrity Solstice cruise on 10 March and departed from it in Dunedin. He returned to Auckland separately.
The ship visited Tauranga, Picton, Akaroa, Port Chalmers and Fiordland.
Health officials will be working with Australian counterparts to detail what the passenger did while on board.
Any New Zealanders on board returning to New Zealand will be regarded as close contacts, put in self-isolation and monitored daily.
