Medical officers have been given the power to quarantine entire vessels as the travel ban on China and Iran and restrictions on South Korea and Italy have been extended.
Prime Minister Jacinda Ardern said on Monday the current border restrictions "remain effective in slowing the virus from transmission here in New Zealand and they remain some of the toughest in the world".
It follows Ardern's announcement last week that travellers from South Korea and northern Italy would be required to self-isolate for 14 days upon arrival in New Zealand, and that the travel ban on China and Iran would be extended until further notice.
Italy has ordered a virtual lockdown across a swathe of its wealthy north, Reuters reported, including the financial capital Milan, in a drastic attempt to try to contain a rapidly growing outbreak of coronavirus.
Ardern said Cabinet has agreed to quarantine measures that mean medical officers of health have powers under the Health Act 1956 to quarantine cruise ships and aircraft coming to New Zealand if it's believed passengers have COVID-19.
"We have not yet had any need for such powers but we must be prepared should the need arise," Ardern said. "This steps up powers from being able to quarantine individuals and extends it to an ability to quarantine entire vessels."
The Ministry of Health confirmed on Monday that there are no additional confirmed or probable cases of COVID-19 - the number of confirmed cases sitting at five with two probable cases.
Eight New Zealanders were aboard the Grand Princess cruise ship currently in quarantine off California, and the Ministry of Health confirmed one of them is a "probable case".
