Eerie footage has emerged showing a mysterious 100 metre-wide black ring of smoke floating over clear skies in Kazakhstan - convincing locals it was caused by a UFO.

The clip was filmed on Saturday in Shortandy village, 40 miles north of the capital Astana, and captures the cloud hovering in the sky for 15 minutes before suddenly vanishing without trace.

The video has been viewed more than 50,000 times since being uploaded to YouTube, prompting all manner of bizarre explanations for the phenomenon - with many seemingly convinced it is definitive proof of extra-terrestrial life.

Spine-chilling: The creepy footage shows a mysterious 100 metre-wide black ring of smoke floating over clear skies in Kazakhstan - convincing locals it was caused by a UFO

Confused locals watched the mysterious cloud hover ominously over Shortandy for a quarter of an hour on Saturday morning before it vanished as quickly as it appeared.

Once the cloud had rapidly dispersed, no trace of it was left in the sky.

Speaking to local news website Today.kz, villager Oleg Menshikov said: 'It was like a black cloud. We saw it at around 4 pm on April 3. It dissipated like smoke, but it was completely odourless.'

Within minutes of the video being shared online, YouTube users began to question whether the thick black hoop was an alien spacecraft, while others suggested it might just be cigarette smoke immediately in front of the camera but giving the perception it is in the sky.

Others thought the cloud was likely to be a naturally occurring weather event known as a thermal microburst, which is caused by a falling mass of warm air.

Mysterious: The clip was filmed on Saturday in Shortandy village, 40 miles north of the capital Astana, and captures the cloud hovering in the sky for 15 minutes before suddenly vanishing without trace

Dispersing rapidly: Confused locals watched the mysterious cloud hover ominously over Shortandy for a quarter of an hour on Saturday morning before it vanished as quickly as it appeared

Experts believe the cloud was roughly 100 metres in diameter and floated close to a mile in the air.

Speaking to Russia Today, Andrey Solodovnik - associate physics professor at the Northern Kazakhstan State University - dismissed suggestions the cloud was caused by aliens.

He said that based on similar clouds seen in the skies in recent years, the giant black hoop was likely to have been little more than a smoke ring generated by combustion at nearby factories.

Plenty of industrial machinery is known to create ring-shaped clouds of smoke, though these are usually lighter-coloured, considerably less dense and vanish in just one or two minutes.