German police trainees are under investigation after they reportedly started a brawl in Berlin and vandalised public property while shouting "Heil Hitler".

Seven men aged between 19 and 25 were arrested on Monday evening (4 November) after a witness reported that they were attacking public property. The man said he overheard one trainee shouting "Heil Hitler".

The witness called the police when he spotted the men kicking electricity and telephone boxes in central Berlin. When the police arrived and took the details, they realised that the men were trainees at the police academy.

"We will look very closely at this incident," police chief Klaus Kandt said. "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 force is trying to clean up its act after several controversies earlier this year tarnished its reputation.

In November, it was accused of having been infiltrated by Arab criminals. The German Police Union said there were clear indications that Arabic mafia families had infiltrated the capital's police academy after a female recruit of Arab origin was caught taking pictures of confidential information and transmitting it on Whatsapp.

Kandt described the accusations as "categorically false, unfounded and defamatory." He said that within the police union people were intent on "stoking racism".

In June, several Berlin police officers who were in Hamburg for the G20 were sent home early after they held a wild party involving public sex, brawling and mass urination.

"They drank, danced, pissed and, yes, apparently also bonked, as our press officer put it so well," the force said in a statement. The Berlin police said it would investigate the incident after acknowledging that the officers' behaviour did not meet the standards expected of public servants.