Alien worshippers are urging the Government to admit extraterrestrial life is out there after the release of thousands of secret files on UFO sightings.

The Defence Force released thousands of documents detailing alleged UFO sightings between 1952 and 2009 on Wednesday.

They include a report into the famous 1978 Kaikoura sighting, where a small plane was tracked by a large cluster of fast-moving bright lights for about 20 minutes.

Aetherius Society NZ organiser Frank McManus says the documents prove the New Zealand Government knows about the existence of alien life.

He is calling for a full state investigation of the sightings.

"The first stage now is for governments to admit to the people that UFOs are visiting this world. They should be admitting these people saw what they saw.

"The next stage is to investigate further. There has to be something beyond this. Not just the release of files but serious investigation.

"The next question will come from the people - 'why are they here?'."

The Aetherius society was started by in 1955 by the late yoga guru George King.

Its members claim to be in touch with alien life, or 'Cosmic Masters', who give messages on how to halt Earth's slide into ruin.

Mr McManus says aliens are more closely connected to the spiritual realm than humans, who are tainted by the existence of nuclear weapons and war.

He claims successive governments around the world have covered up the existence of UFOs.

"It's hard to say whether New Zealand was part of it, but there has been a cover up. The American Government has been part of it."

Mr McManus says he is hopeful the release of UFO files will spark a change in New Zealand society's attitude to the possibility of alien life.

"This prepares the public mind for a little bit more," he said.

"It's a massive shift. Like when we found out the world was round, not flat. We imprisoned that guy and burned his books, but he was right.

"We shouldn't be afraid of a quantum shift like that."

Other nations including Britain and Brazil have also released Government files on alleged UFO encounters.

The New Zealand Defence Force has said it will not comment on the files, as it was only a collection point for the documents and did not have the resources to investigate or verify their contents.