Wellington, Dec 17 NZPA - A hunt is on to find around 30 passengers who may have been exposed to measles after sitting near a baby with the disease on a recent flight from Auckland to Christchurch.

Canterbury Medical Officer of Health Dr Ramon Pink said the 11-month-old was on flight NZ509 on December 7.

"Passengers sitting in rows 13-17 of the Air New Zealand flight which arrived in Christchurch from Auckland at 3.45pm on Monday (December 7 ) may have been exposed to the highly infectious disease," Dr Pink said.

People sitting in those rows should contact their doctor or call Community and Public Health on (03) 364 1777 if they had had symptoms.

"Anyone sitting in these rows is also urged to stay away from pre-schools or other places where young children gather for the next 12 days."

The baby had transferred to the Christchurch flight after landing in Auckland from London.

Measles was spread by breathing, coughing and sneezing, and could cause a rash, high fever, runny nose and sore, watery eyes. It was occasionally fatal.

The measles incubation period was up to 21 days, Dr Pink said.