BERLIN (Reuters) - Police launched dawn raids across Germany on Tuesday on about 190 mosques, flats and offices linked to an Islamist group after the government banned the organization, accusing it of radicalizing youngsters.

Interior Minister Thomas de Maiziere said the DWR “True Religion” group had persuaded about 140 people to join militants in Iraq and Syria.

DWR, also known as “READ!” made no reference to the raids on its website and did not immediately respond to a request for comment. De Maiziere said it had several hundred members.

Pictures showed masked police officers carrying away computers and files from properties.

Chancellor Angela Merkel has come under pressure to harden her line on security after several attacks claimed by Islamic State across Europe, including a bombing and a knifing in Germany that wounded some 20 people in July. She is also under fire for letting in about 900,000 migrants, mostly Muslims, last year.

Some Syrians in Germany say many mosques here are more conservative than those at home, and that they are confronted by Muslims who insist on a literal interpretation of the Koran.

Last month, a Syrian committed suicide in prison after he was arrested on suspicion of planning to bomb an airport. His brother and friends have said he was “brainwashed” by ultra-conservatives imams in Berlin.

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The Bundesverfassungsschutz domestic intelligence agency estimates that there are about 40,000 Islamists in Germany, including 9,200 ultra-conservative Islamists known as Salafists, Hans-Georg Maassen, who leads the agency, told Reuters in an interview on Tuesday.

“There are about 500 people that the police consider dangerous,” he said. “We remain a target of Islamic terrorism and we have to assume that Islamic State or other terrorist organizations will carry out an attack in Germany if they can.”

De Maiziere said Tuesday’s raids in 10 German states were the biggest crackdown on any group since the government shut down a movement known as Kalifatstaat (Caliphate State) in 2001, accusing it of extremist activities.

He said DWR had distributed Korans and other religious material especially to young people, but this was not the reason for the ban.

“Today’s ban is rather directed against the abuse of religion by people propagating extremist ideologies and supporting terrorist organizations under the pretext of Islam.”

Maassen said the ban - which had been carefully prepared to ensure it could not be overturned by the courts - could prompt large numbers of people to withdraw from the Salafist scene, or at least reduce their missionary work.

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“The decisive issue now is that the evidence has to be examined to understand how the organization funded itself and who else was behind it as supporters and financiers, so that we can take additional measures,” he told Reuters.

He said there was evidence that a foundation in Bahrain had paid for Korans used by the group, but did not name the foundation and gave no further details.

DWR members have tried to hand out material in German town centers to passers-by, often holding banners or wearing garments with the word “READ!” emblazoned in gold. The ban means they are now prohibited from running such campaigns.

Fears about the number of migrants entering the country have boosted support for Alternative for Germany (AfD), a populist party that says Islam is incompatible with the constitution and has siphoned off support from Merkel’s conservatives.

A spokeswoman for the interior ministry said there was no indication that DWR was planning attacks itself. Overall, some 820 people have left Germany for war zones in Syria and Iraq, and officials fear they may pose a security threat on their return.