is that it was the moon, or debris left on the lens

Conspiracy theorists have accused Nasa of cutting its live feed from the International Space Station whenever a 'UFO' appears.

On two separate occasions this month, alien hunters claim to have spotted mysterious objects appearing on their screens before it goes blank.

UFO watcher Toby Lundh recently spotted a UFO outside the space station, moments before the stream was interrupted for 10 to 15 seconds.

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Last week, a grey object was seen coming up over the horizon and then disappearing moments before Nasa switched to a different camera. One possible is that it was a bit of debris that hit the lens, or even the moon

Mr Lundh told Disclose.TV that there are 'always some UFOs showing up,' and 'Nasa always cuts the feed when a UFO gets close to the station.'

The alien hunter claims to have captured a still photo of the unidentified object from the feed - and it looks remarkably like the Starfleet insignia in Star Trek.

He also says that Nasa has removed the recording from its archives as part of efforts to conceal alleged communication between astronauts and UFOs

In a separate incident last week, a grey object was seen coming up over the horizon and then disappearing moments before Nasa switched to a different camera.

UFO watcher Toby Lundh recently spotted a UFO outside the space station, before the stream was interrupted for 10 to 15 seconds. The alien hunter claims to have captured a still photo of an unidentified object (pictured) that appeared on the live feed on January 6. It look remarkably like the Starfleet insignia in Star Trek

One possible is that it was a bit of debris that hit the lens, or even the moon.

But 'Streetcap1', the YouTuber who posted the video isn't convinced. 'Please bear in mind that the moon appears white when it shows,' he writes.

Meanwhile on October 7, UFO watchers said they witnessed a strange object near the station during a spacewalk by astronauts Reid Wiserman and Alexander Gerst.

The object was later identified as being either a speck of dust or a lens flare from the sun.

That didn't stopped some conspiracy theories arising though, with ufologists somewhat speculatively claiming it was proof that we are not alone in the universe.

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Professor Andrew Balogh from the Imperial College London Department of Physics tells MailOnline: 'Generally speaking UFO sightings are either explained by some artefact effect - even some space junk - or left unexplained as there is not enough evidence.

'It's difficult to judge from the video in this instance, because of its poor quality. If Nasa has access to high quality images, they may investigate further.'

Nasa is yet to comment the incidents.

The space agency's ISS live stream and rover photos have become a huge source of 'evidence' for conspiracy theorists.

Many scientists believe UFO sightings such as this are down to a psychological phenomenon called pareidolia.

This describes the brain's response to seeing significant objects in random places.

'The vast majority of these images are as vague and elusive as those posted by UFO witnesses on Earth, and many have a fairly mundane explanation, 'Nigel Watson author of the UFO investigations Manual told MailOnline.

'The problem is that the more Nasa denies such things or explains them the more people think there is a conspiracy to hide the truth that aliens are visiting our planet.'