Approximately 400 individuals gathered outside Frankfurt's Festhalle concert hall on Sunday ahead of the evening's planned performance by Roger Waters, a contentious British rock musician.

The protesters were taking a stance against anti-Semitism, hatred of Israel and against conspiracy theories, Michaela Fuhrmann, head of political relations of the German city's Jewish Community, told Deutsche Presse-Agentur (dpa).

Participants held signs saying "Israel, we are by your side" and "Roger Waters, wish you were not here," in reference to one of the most famous songs by the group Pink Floyd that Waters co-founded in the mid-1960s.

The action follows accusations of anti-Semitism by Waters, who earlier in May also caused outrage in Berlin when he performed in a Nazi-style uniform and aimed an imitation machine-gun at the audience.

In a statement released by a German law firm on his behalf, Waters said the performance only harked back to the imagery used in Pink Floyd's iconic album and film "The Wall." He said he was opposed to authoritarianism and noted that his father died fighting the Nazis in World War II.

Meanwhile, authorities in Berlin were investigating his two recent Berlin performances for possible "incitement of the people."

His concert in Frankfurt was originally to be cancelled because of accusations of anti-Semitism. Waters in April successfully had this overturned in a Frankfurt court, which in its ruling invoked artistic freedom.

The Festhalle venue of the concert was where more than 3,000 Jewish men were rounded up, detained, mistreated and finally deported on the Kristallnacht pogrom night of Nov. 9-10, 1938.