The number of UFO sightings reported to the Ministry of Defence (MoD) trebled in the year its hotline was closed, newly released files show.
The MoD closed its desk in 2009, saying it served "no defence purpose" and was taking staff away from more valuable "defence-related" work.
Its decision came in a year when officials had received a surge in the number of reported sightings.
According to a briefing in the files, during the years 2000-07 the MoD received an average of 150 reports per year.
But by November 2009, it had already received 520 reports that year, as well as 97 freedom of information requests on UFOs.
Possible reasons for the increase included the craze for releasing Chinese lanterns at weddings and public holidays, appearing as floating lights in the sky.
One example included a sighting by soldiers in Shropshire which hit the headlines in June 2008.
More top news
Seventeen people – including nine members of the same family – were killed in the accident.
A group of MPs and peers has said the roll-out of the project should be reviewed immediately.
The ex-combatants were sworn in on Friday.