An astonishing top secret video just released by the Chilean Navy may be the most definitive proof of a UFO ever.

The incredible footage shows a black coloured object flying across the sky, before leaking some kind of unknown substance into the atmosphere.

Authorities have examined every aspect of the exceptional video but after two years, they claim to have no idea what it is.

A Chilean Navy helicopter filmed the spectacular footage of the object, which appeared to be spraying some kind of gas into the atmosphere, on November 11, 2014.

Chilean government agency CEFAA (Comité de Estudios de Fenómenos Aéreos Anómalos), which investigates UFOs, took the tapes for examination, reports Daily Star.

But after two years investigating they finally released them to the public this week.

General Ricardo Bermúdez, Director of CEFAA, told Huffington Post: “We do not know what it was.”

The helicopter pilot, a Navy Captain with years of flying experience, described the object as a “flat, elongated structure” with “two thermal spotlights like discharges that did not coincide with the axel of motion.”

The technician onboard said it was “white with a semi-oval shape on the horizontal axis.”

Nuclear chemist Mario Avila, a CEFAA scientific committee member, conducted interviews with the two men on the chopper.

“I was very impressed by these witnesses,” Avila said.

“They were highly trained professionals with many years experience, and they were absolutely certain that they could not explain what they saw.”

Air Force photo analysts confirmed that the object was a real, three dimensional form with volume and that had “control in its movements.”

A CEFAA investigation went over every aspect of the bizarre video, but still have absolutely no idea what it could be.

The organisation was also responsible for the investigation of a UFO two years ago, which baffled experts.

They confirmed that there was no evidence of hoaxing or of "alteration of the video".

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Committee members analysing the footage also claimed there was no way it could be a passenger jet coming into land at Santiago airport.

They were also unable to establish what "material" was being thrown out by the unidentified flying object.

They also ruled out a bird, flying insect, drone, parachute or hang glider.

Whatever the strange object was remains a mystery.

Earlier this week experts were baffled by what looked like a crashed UFO at the bottom of the sea.

Scientists have also been investigating "alien sounds" coming from deep space.