The Staatsschutz (the political crime unit) are now investigating the case after the witness initially claimed that one of the men shouted the words “Heil Hitler.” During later questioning at the police station the man was not able to definitively say whether he heard those words.

The 40-year-old man had called the police after he witnessed the group of men shouting loudly and kicking electricity boxes and telephone junction boxes. When police officers tuned up they took the men’s details and at that point discovered that they were police academy trainees.

“We will look very closely at this incident,” said police chief Klaus Kandt on Tuesday. “Regardless of whether something criminal happened here or not, I expect that all trainees with the Berlin police act in a respectable way in their free time.”

The Berlin police have had their image tarnished by several controversies this year.

In November police chiefs were forced into a public denial of claims that their academy had been infiltrated by Arabic crime syndicates.

German Police Union spokesman Bodo Pfalzgraf sparked the controversy by telling broadcaster ZDF that there were “clear indications” that Arabic mafia families had developed a strategy of placing family members inside the police force.

Police chief Kandt dismissed the claims as “categorically false.”

“Nobody who has made complaints has presented any proof,” he said.

Meanwhile in June, a unit of the Berlin police that had been sent to Hamburg to secure the city during the G20 summit were sent home early after they held a raucous party at their lodgings.

Witnesses reported seeing the officers having public sex and urinating in groups on fences. Police chiefs in the capital announced an internal investigation into the incident, after admitting that the officers’ behaviour did not meet the standards expected from public servants.