Authorities in Germany have warned that anyone dressing as a “killer clown” to frighten people risks a year in prison as the craze spreads to the country.

Police arrested a man over the weekend after he terrified passengers by roaming a train wearing a clown mask and carrying a knife.

A few days earlier a teenager was left with injuries after he was attacked with a baseball bat by a man dressed as a clown.

Authorities across Germany have called for prosecutors and police to take a hard line in response to the craze.

“Anyone who wants to scare another person to death, as the saying goes, is not funny but a criminal," Thomas Kutschaty, the justice minister in North Rhine-Westphalia, Germany’s most populous state, told Bild newspaper.

Even if the victim was not physically harmed, dressing up as a clown to frighten some one constituted a “criminal threat”, Mr Kutschaty said.