WELLINGTON, Jan. 13 -- New Zealand's national carrier said on Tuesday it was canceling flights to the Pacific island nation of Tonga because of ash and smoke from a volcanic eruption.

A return service from Auckland to Nukualofa was diverted to Samoa on Monday and a second return service on Tuesday had also been canceled, said a statement from Air New Zealand.

The airline had scheduled additional services later in the week, but these were subject to conditions improving.

New Zealand Civil Aviation Authority meteorologist Peter Lechner told Radio New Zealand on Tuesday that the Hunga Ha'apai volcano, about 62 km from Nukualofa, was sending volcanic ash more than 9,000 meters in the air.

Strong westerly winds were expected to dissipate the ash if there were no further eruptions.

The New Zealand government's Institute of Geological and Nuclear Sciences (GNS Science) was sending volcanologists to Tonga to help observe the eruption, which has been underway since late last month.

GNS Science volcanologist Geoff Kilgour said that as long as air traffic was possible, the two scientists would make observation flights close to the vent to determine the amount of ash in the plume.