A mysterious new video has emerged which conspiracy theorists believe may show a UFO in the sky over Italy.

An unusual bright green spherical object, which changes shape and colour in the four minute video, was caught on camera in Salento this week.

It is unclear what the object is, but the video is said to be completely genuine, untampered footage.

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The video was posted on Facebook by Lucio Margiotta, a music teacher at the Music Academy of Salento, who saw the light in the sky at around 8pm local time.

Mr Margiotta said: ‘UFO sighting of 9/1/2017 at about 19.38 hours. I don’t know what was and what it is to call it but it is very strange.’

In the film, a bright white, spherical object can be seen in the sky, which appears to change shape, size and colour.

At one point it turns a bright green colour, and becomes a ring, similar to a smoke ring.

Finally, the ball splits into two, before quickly fading away.

The video was shot on a smartphone at maximum (x8) zoom, and Mr Margiotta said that no filters or effects were applied.

It is unclear what the object is, although the fact that it was filmed on a smartphone suggests that the rings may be a result of autofocus, distorting the image.

Nigel Watson, author of the UFO Investigations Manual, told MailOnline: ‘It is noteworthy that the distant light only turns into a halo when Lucio Margiotta zooms in on it, which suggests that the autofocus system of the camera is distorting the light to produce this unusual effect. 

‘It would be interesting to know if the witnesses saw this light turn into a halo, or whether they just saw a distant light.’ 

In the comments on the Facebook video, others have suggested that the phenomenon may be Venus.

Emy Negro said: ‘was Venus … the highest peak of visibility of this planet goes from 19:30 to 20:00 … if there is little haze is more visible.

‘The circle you saw was merely caused by the zoom of your camera…you were trying to focus and the image distorted.’

But others were convinced that it was a sign of alien life, such as John Martin, who said: ‘They visit me at my home on a regular basis. They are the sphere beings.

‘If you speak to them as friends and wave, they often will respond with a bright flash.’

While some are convinced that flying saucers exist, most sightings turn out to be man-made objects such as weather balloons or satellites, or down to natural phenomenon like ball lightening or meteors.