A Ministry of Health statement confirmed the additional cases this morning after test results for the crew members were received late last night.
Yesterday two cases were revealed after rapid testing on symptomatic crew members came back positive.
The nine positive cases come from a total crew of 21 people.
The Mattina is quarantined in an area of the port inaccessible to the public, with additional fencing being erected to further restrict public access to the area.
No crew members have come ashore, and the only South Port employee to board the vessel was a harbour pilot who boarded the ship to guide it into port.
It is mandatory for a pilot to board a ship of this size when berthing, and the pilot in this case was fully vaccinated and wearing personal protective equipment (PPE).
The Mattina's positive Covid results follow those reported on Spanish-flagged vessels the Viking Bay and the Playa Zahara, which is docked at Lyttelton, in recent weeks.
A total of 16 of the 18 crew of the Playa Zahara last week tested positive for Covid-19.
The vessel was brought into Port Taranaki so those on board could be tested before it made its way to Lyttelton Port.
-Additional reporting NZH
