BERLIN – The German police are investigating Roger Waters, co-founder of the band Pink Floyd, who has long been critical of Israel, after he performed in Berlin last week wearing a Nazi-style costume like the one he used to critique fascism in “The Wall”.

Waters, who has made anti-Israel statements in the past that many have said cross a line into anti-semitism, has successfully fought two attempts by German courts to block him from German concert venues in the past.

The investigation is focused on the costume Waters wore during a rendition of the 1979 Pink Floyd song “In the Flesh”, from their seminal album “The Wall”, in which a rock star imagines himself as a fascist dictator. Similar staging was featured in the 1982 movie “Pink Floyd: The Wall”, featuring Bob Geldof.

During parts of the concerts in Berlin, on May 17 and 18, Waters wore a black trench coat with epaulets and a red armband, according to videos posted to social media and witnesses. Flanked by men dressed in costumes that evoked Nazi storm troopers, he shot a prop machine gun into the audience.

Waters has worn similar costumes at concerts outside of Germany for years for the routine, which he has called satire.

Berlin authorities will have to determine to what extent the display of Nazi-like imagery is protected by artistic freedom of expression. In Germany, displaying Nazi symbolism, such as swastikas or SS regalia, justifying or downplaying the Holocaust, and antisemitic acts are illegal.

“Artistic freedom of expression is not a licence to incite hatred,” Mr Nicholas Potter, a researcher with the Amadeu Antonio Foundation in Berlin, a group that tracks neo-Nazism, right-wing extremism and antisemitism in Germany, wrote in an e-mail exchange.

“Artistic freedom is often used as an argument to express anti-democratic or hateful views, including antisemitic ones, but that doesn’t always mean it’s applicable – the context is crucial,” he added. Mr Potter attended one of the Berlin shows and wrote about it on the foundation’s news blog.

Waters initially agreed to an interview...