A police officer contacted British UFO experts after seeing three aliens examining a freshly made crop circle near Avebury, Wiltshire.

The sergeant, who has not been named, was off-duty when he saw the figuresstanding in a field near Silbury Hill, and stopped his car to investigate.

However, as he approached the 'men' – all over 6ft tall with blond hair – he heard "the sound of static electricity" and the trio ran away ''faster than any man he had ever seen''.

The officer returned to his home in Marlborough, Wiltshire, and contacted paranormal experts and told them he had spotted a UFO.

Wiltshire Police has refused to comment on the incident, saying it is a ''personal matter'' for the officer involved.

Crop circle researcher Andrew Russell, who is investigating the bizarre sighting on behalf of the officer, described the moment his sighting was made.

He said: ''At first he thought they were forensic officers as they were dressed in white coveralls. He stopped his car and approached the field.

''The figures were all over 6ft and had blond hair. They seemed to be inspecting the crop. When he got to the edge of the field he heard what he believed to be a sound not dissimilar to static electricity.

''This crackling noise seemed to be running through the field and the crop was moving gently, close to where the noise was.

''He shouted to the figures who, at first, ignored him, not glancing at him. When he tried to enter the field they looked up and began running.