"No tolerance for Salafists" said the conservative Welt newspaper after a small group of men, wearing orange vests with "Shariah Police" written on them, went on a series of "patrols" in the western city of Wuppertal.
Seeking to enforce their austere moral code, they told Friday nightclub-goers to refrain from drinking alcohol and listening to music and arcade customers not to play games for money.
A video circulating online shows among them Sven Lau, a German Salafist convert who claims to be one of those behind the patrol idea.
Under current German law, the self-styled "Shariah Police" could at most face a charge of disturbing public order.
No arrests have been made so far, but political leaders warned they would crack down on the Islamist patrol if it took its campaign any further.
"We will not tolerate an illegal parallel justice," warned Justice Minister Heiko Maas.
"Sharia law is not tolerated on German soil," Interior Minister Thomas de Maiziere told Saturday's Bild newspaper.
Bavaria state's interior minister Joachim Herrmann described it as a"direct attack by the Salafists on our rule of law" in comments published in Monday's Bild daily.
Stephan Mayer, also from the CSU Bavarian allies of Chancellor Angela Merkel's conservatives, called in Sunday's Tagesspiegel for promoting strict Sharia law to be "penalized".
Volker Kauder, the parliamentary group leader of Merkel's conservatives, argued that the police alone was responsible for upholding public order.
"Therefore we must examine a ban of these supposed guardians of Islamic virtues," he told the Welt am Sonntag.
The head of the Central Council of Muslims in Germany has also condemned the action by the Salafists in Wuppertal.
"Salafists and fanatics should no longer be able to hide behind religious freedom, even Islamic groups concerned with the reputation of Muslims see it that way," said Welt.
Rainer Wendt, head of police union DPolG warned that the so-called “Sharia Police” should not be taken lightly.
“At any time such groups could make people all over Germany feel insecure and test our rule of law.”
He added the actions by the Salafists in Wuppertal could be a “test run” for other areas, Wendt added.
But writing in the Tagesspiegel newspaper, journalist Malte Lehming pointed out that Christian groups had long carried out action in the centre of Hamburg’s red light district, the Reeperbahn.
Lehming added that freedom to preach religious beliefs was protected in the German constitution. “As long as ‘Sharia Police’ and singing evangelists don’t force anybody into something, they can do what they want. A knee-jerk reaction only plays into the hands of the Islamist provocateurs."
German intelligence last year voiced concern over the growing number of Islamic Salafists, who espouse an austere form of Sunni Islam, and said they numbered around 4,500 in the country.
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