A police helicopter hovering over Bristol captured some footage of a "heat-emitting UFO." Though it was not visible, it looked like a "dark, circular shape" in the sky.

Shot on Saturday, September 17, by thermal cameras, the footage was shared online by NPAS St Athan or the National Police Air Service with its base in South Wales.

While some police monitors gave a few interpretations of the sights, they later admitted that they did not have a clue as to what it could be.

In Twitter, the police said that the footage, which shows 8.30 p.m., was shot at 9.30 p.m. at a time when it was "pitch dark." It was shot "over the Bristol channel at approx 1,000ft."

It was a portion of a long video, was posted on September 23, on which they asked: "Any suggestion?? Nothing seen by local ATC."

As the filming was set to 'black hot', it seemed to indicate heat emanating from the craft.

"Really difficult to judge the size but we filmed it for just over seven minutes as we were coming back into land," they added.

Many skeptics have not been convinced. Some asked whether it was a balloon or a lantern - a debatable point, as the object was not even visible to the naked eye.

"We really don't know but doubt it was a lantern as it was going into the wind," said the pilot.

One commentator who called himself UFOs-Exposed said: "the pilot [says] the object wasn't visible in daytime mode, only the camera's infrared mode."

YouTube/beamsinvestigations1