It's a mystery worthy of Mulder and Scully, and is sure to deepen the suspicions of conspiracy theorists. The Australian military has lost its X-Files.

After a two-month search, in response to a newspaper Freedom of Information request, Australia's Department of Defence was forced to admit that it could not find the documents.

They detail sightings of Unidentified Flying Objects, or UFOs, across the vast, sparsely populated country.

'The files could not be located and Headquarters Air Command formally advised that this file is deemed lost,' the department's FOI assistant director, Natalie Carpenter, told the Sydney Morning Herald.