Police received eight sightings in Northern Ireland during 2021, an increase from six such reports in 2020 and four in 2019.
These included a report of a space ship and flashing lights in the Downpatrick area on January 17.
In May, police received two sightings reports, one of white lights following a helicopter in the Maghaberry area and an odd disc seen in the sky in the Slemish area of Co Antrim at the end of the month.
In July, there was a report of “strange images” on closed-circuit television (CCTV) in a house in the Newtownabbey area and a dome-shaped object with eight lights in the sky reported in the Saintfield area.
In September, a report was received in the Lisburn area of “aliens in bedroom”, while in October a detained patient reported having been abducted by aliens.
The final report of the year was of “unusual bright lights in the sky” received in November.
UFO sighting reports on the Police Service of Northern Ireland database include Unidentified Flying Objects (UFO), Ariel Phenomena, Unidentified Ariel Phenomena, Lights In The Sky, Aliens and Extra-Terrestrial.
A PSNI spokesperson told PA that no investigations were carried out in relation to these incidents.
Nick Pope, who used to investigate reports of UFO sightings for the MoD, said it is possible that more people spending more time at home during the pandemic may account for a rise in reported sightings.
“It’s difficult to say what lies behind the small increase in sightings,” he told the PA news agency.
“Covid-19 and lockdowns may have played a role, with people having more time on their hands during the pandemic, and perhaps spotting things that previously may have gone unnoticed.
“Another possibility is that people are following the situation in the United States, where Congress is taking the issue seriously and the Pentagon has launched a new UFO initiative.
“This may make people more likely to report something unusual that they’ve seen, because it sends the message that the authorities take the matter seriously.”
However Mr Pope said he believes the true number of sightings is much higher.
“Sadly, the numbers are still fairly low, and I suspect there’s chronic underreporting, perhaps because of the perceived stigma,” he said.
“That’s possibly a consequence of the Ministry of Defence’s decision to stop investigating UFOs at the end of 2009.
“If the MoD restart investigations and ask the public to report anything unusual, I’m sure they’ll receive lots of reports.”