The New Zealand military has released hundreds of previously classified reports, detailing claims of unidentified flying object (UFO) sightings and alien encounters.

The reports, dating from 1954 to 2009, were released under freedom of information laws after the New Zealand defence force removed names and other identifying material.

In about 2,000 pages of documents, members of the public, military personnel and commercial pilots outline close encounters, mostly involving moving lights in the sky.

Some of the accounts include drawings of flying saucers, descriptions of aliens wearing "pharaoh masks" and alleged examples of extraterrestrial writing.

Before their release Air Force Squadron Leader Kavae Tamariki said the defence force did not have the resources to investigate UFO sightings and would not be commenting on the files' contents.

"We've just been a collection point for the information. We don't investigate or make reports, we haven't substantiated anything in them," he told the Dominion Post.

One of the most comprehensive files concerns two sightings of strange lights off the South Island town of Kaikoura in 1978, one of which was captured by a television crew aboard a plane in the area.

The incident made international headlines at the time but a contemporary Air Force report found it could be explained by natural phenomena such as lights from boats being reflected off clouds or an unusual view of Venus.

The original documents on which the reports were based will remain sealed in the national archive, some until 2080.

- AFP