Doctors in masks and white gowns boarded an Air New Zealand plane grounded in Auckland after passengers and crew on board fell ill, a woman who was on the flight says.

Five passengers and one crew member became ill on board flight NZ281 from Singapore, which landed at Auckland International Airport on Friday night.

A spokeswoman for Air New Zealand said one of the people on board was taken to Middlemore Hospital, as a precautionary measure.

The plane landed at 10.35pm and passengers were not allowed to disembark until 11.50pm.

Passenger Aivy Kurian was travelling with her two young children, Emma, 4, and Noeline, 1.

She said while passengers were waiting to board the plane in Singapore, she saw a teenage boy vomiting, and he later boarded the plane.

During the flight, she could hear someone being ill but could see who it was.

About half an hour after the plane landed in Auckland, a group of doctors with “masks and white gowns” boarded the plane.

Kurian said she saw the same teenage boy being assessed by doctors.

An Air New Zealand spokeswoman said the airline was in direct contact with the regional health authority, which confirmed there was insufficient information to know what may have caused the passengers and crew member to become ill.