The UFO allegedly responsible for wrecking a wind turbine could have been a secret unmanned stealth bomber on test flights.

The claim came from Ministry of Defence insiders who reportedly said that a black delta-wing craft called Taranis was making test runs on the coastal bombing ranges at Donna Nook and North Coates in Lincolnshire, near to the site of the damaged turbine.

The Taranis, named after the Celtic god of thunder, is about the same size as a Hawk jet and is equipped with stealth equipment and an 'autonomous' artificial intelligence system.

Theory: Government officials claim the Taranis was making test flights near to the area where a wind turbine was destroyed

The plane is being developed by BAE Systems and has been designed to deliver weapons to battlefields in other continents.

The UFO was spotted by hundreds of witnesses with many believing it was the work of an 'alien' craft.

One saw orangey-yellow spheres skimming across the sky.

Another reported a 'massive ball of light' with 'tentacles going right down to the ground'. 

Then witnesses told of an earsplitting bang at 4am. Come dawn and the plot thickens.

At the nearby wind farm one of the 60ft blades from a 200ft turbine was found ripped off. Another had been left twisted and useless.

Mystery: The damaged wind turbine, with one of its blades ripped off, in Conisholme, Lincolnshire

So far, so mysterious, except  -  of course  -  to the UFO experts.

For them, the strange goings on at a wind farm in Conisholme, Lincolnshire, can be explained by a flying saucer crashing into the turbine in a close encounter that could, at last, provide the evidence of other life forms they have been waiting for all their lives.

John Harrison, of nearby Saltfleetby, saw the ball of light and its 'tentacles' over the farm. 'It was an incredible sight, I have never seen anything like it before,' he said. 'I have no idea what it was.'

Broken blade: The damaged wind turbine at the centre of the Lincolnshire UFO mystery

Lesley Whittingham tried to photograph the scene. 'It looked like a giant explosion in the air,' she said.

Dorothy Willows saw orangeyyellow spheres. 'I don't believe in UFOs but it was a low-flying object,' said Mrs Willows. Her husband Stephen was woken by a sudden noise hours later on Sunday morning when the damage to the turbines happened.

Could that have been the sound of a UFO hitting it?

Council chief Robert Palmer said he had seen a 'round object with a slight red trim hovering near the top of the turbines' that night too.

'When I heard what had happened I was slightly worried so I've called for a full health and safety review,' said Mr Palmer, 66.

'If the aliens are coming, I want to be there to meet and greet them.'

Yesterday your reporter visited the scene and, while I failed to see any little green men, I did find four little men in green uniforms.

But they had arrived by van, not spaceship, and worked for Ecotricity, the company that built the wind farm.

UFO expert Nick Pope, a former head of the Ministry of Defence's UFO Project, said: 'This is a really bizarre case. What's particularly exciting is that because there's been a collision, there will be residue of the object involved.

Witness: Lesley Whittingham took a photograph of the lights, below.  She said they remained in the sky for several minutes

'Forensic science will enable this material to be recovered and analysed. This elevates this UFO case, because with most sightings all you have is eyewitness testimony or indistinct and shaky film footage taken on a mobile phone.'

Despite his confidence in obtaining hard evidence, a glance around the bleak Fenland landscape provided another mystery.

Having travelled billions of miles to visit Earth, why would our alien friends land in the hamlet of Conisholme, where there are no shops and no pub, but oddly there is an ice cream parlour?

The thought had crossed the mind of the nearest resident to the wind farm.

The woman, who gave her name as Sheila, said she saw or heard nothing on Sunday night and added: 'I hope that one day we will see aliens, but I doubt it will happen in that field.

'I've lived here for 20 years and nothing interesting has ever happened here.'

The location of the windfarm, near North Somercotes in Lincolnshire