David Clayton, a former Royal Air Force Engineer, says the security service MI5 paid people to create fake crop circles to hide genuine proof of UFO sightings.

Clayton says MI5 wanted to cover up UFO sightings said to be real, according to the U.K.'s Express.

Clayton is an expert at crop circles and animal mutations, both which are said to occur when aliens visit Earth. He told the UFO Truth Magazine international conference of the MI5's plot to hide the truth that aliens have visited this planet.

Clayton said he saw crop circles in the 1980s not created by hoaxers and had to be alien-made. He said the plants within the circle were not flattened by physical force but instead by heat.

UFO believers say crop circles are created when an alien saucer lands in a field. 

Clayton admitted most crop circles spotted in the 1990s were fakes but said there were some real ones found.

Clayton says British intelligence had created fake crop circles to make evidence of UFOs seem ridiculous.

"MI5 were paying people to muddy the waters," he said.

Another UFO researcher Gary Heseltine, who organized the conference, said authorities deliberately created a policy to downplay or debunk any unexplainable activity. 

Heseltine also criticized the media for not taking crop circles and UFOs seriously. He said UFO believers are "tired of being ridiculed" for their beliefs.

"The press are not doing you a fair turn. It's time to lift the blinkers a bit and look at the very best evidence," he said.

"If you do that, you will have overwhelming evidence that ET is here and has been for many years."