Police are hunting a 19-year-old suspected of murdering a nine-year-old boy, and boasting about the killing in an online video.

Authorities in the west Germany city of Bochum received a call from a member of the public who feared a killing had taken place in the nearby town of Herne.

Officers searched the basement of a house and found the body of the boy who is believed to be a neighbour of the suspect.

A photo showing the suspect - named by police as Marcel Hesse - bragging about the killing was circulating on the so-called darknet, which is invisible on the open internet and is used by criminals.

The photo has since appeared on regular social networking sites, a police spokesman said.

Police warned that Hesse, who is unemployed and was previously unknown to police, could be armed and dangerous.

He was described as being thin, of average height, with short blond hair and glasses, and wearing clothes with a camouflage pattern.