Australia is stepping in to help 11 New Zealanders still on board the coronavirus-hit cruise ship docked in Japan.

The Kiwi passengers are among thousands who remain on board the Diamond Princess during a 14-day quarantine that is due to finish on Wednesday, if all goes well.

Prime Minister Jacinda Ardern confirmed Australia's assistance in an interview with Newstalk ZB's Mike Hosking this morning.

She said she had spoken with her Australian counterpart, Prime Minister Scott Morrison, about the evacuation of New Zealanders on the ship.

She said Australia had a plan in place to get its citizens on the ship back home safely. Any evacuation plan would also include getting those 11 Kiwis back home too, she said.

"They haven't confirmed - locked - anything yet. But they have said that if they do, they will bring our 11 New Zealanders home.

"Of course we will then make our own plans to have them relocated from Australia to New Zealand and then deal with public health quarantine issues from here."

Japanese authorities yesterday confirmed there have now been 355 confirmed cases, in total, since the ship docked in Yokohama on February 3.

Among those affected are two New Zealand citizens who have been hospitalised.

Australian media are reporting that the evacuation is expected to happen within days.

The country's national security committee met with Cabinet members last night, The Australian reported.

It said a final decision on the details of the rescue - detailing when and how it would take place - is expected as early as today.

Details about where those passengers will be quarantined when they arrive are also expected in due time.

Up to 200 Australians are on board the plagued ship. Of those, 16 Australian citizens have tested positive for coronavirus, now dubbed Covid-19.

Moves to get Australian and New Zealanders off the cruise ship come as the US Government has successfully removed up to 380 of its citizens who were on board.