Police in the western German city of Essen are investigating after people waved black banners with Islamist slogans in Arabic, including one calling for the establishment of a caliphate, at a march on Friday evening.
Some participants also held up their index fingers, in a gesture closely associated with radical Islamists.
Aiman Mazyek, the chairman of the Central Council of Muslims in Germany, appealed to Muslims to “be careful who you walk with” in an interview with Deutschlandfunk public radio on Saturday.
Police in Essen said the pro-Palestinian theme of the rally appeared to have been a ruse, with the true intention to hold an Islamist march through the public streets. An estimated 3,000 people attended the demonstration.
The heavy contingent of police officers that accompanied the march on Friday evening did not report any criminal offences, but a police spokesman said on Saturday that police and the local public prosecutor’s office would now “meticulously investigate” whether laws had been broken.
Hate speech, incitement, and expressions of support for violence and terrorism can be criminal offences in Germany.
On Friday evening, a police spokesman described the demonstration as “very loud and very emotional, but peaceful.”
Authorities had warned that they would take action over any violence and had issued a number of conditions before allowing the march.
German authorities have taken measures to limit, or in some cases outright ban, pro-Palestinian rallies in recent weeks, citing concerns over the repeated use of anti-Semitic slogans and expressions of support for Hamas.
On Friday, nine people were detained at a pro-Palestinian rally and demonstration in Frankfurt, according to police.
A major rally organized by several pro-Palestinian groups is set to take place in Berlin later on Saturday. Organizers expect several thousand people to attend.