German police launched simultaneous raids in six cities across the state of North Rhine-Westphalia (NRW) on Saturday evening, with some 1,300 officers sweeping shisha bars and other venues in Dortmund, Essen, Duisburg, Bochum, Recklinghausen and Gelsenkirchen.

Authorities said they were targeting family crime clans of Arabic background in the northwestern state. According to the mass-circulation Bild daily, police are focusing on Arabic crime syndicates, especially those with Lebanese background.

Police spokesman Oliver Peiler told reporters that the coordinated raids started at 9 p.m. local time (2000 UTC).

"As we do quite often, tonight we are checking numerous shisha-bars (…) because the shisha bars act as sanctuaries for members of these family clans," he said.

Clans also use shisha bars, cafes, and gambling venues for money laundering and other illegal business activities, according to media reports. Police in Essen tweeted that a man has been detained carrying €9,000 ($10,322) in cash.

"He will now need to prove to the authorities that the money has been obtained legally," they said.

Read more: Italian Mafia, bikers, Berlin clans: Europe's crime gangs

Thousands of members

While dozens of people have been searched and multiple properties swept, police are only expected to release official results of the crackdown on Sunday.

Firefighters, customs officers, members of the tax collection service and communal police officers were deployed alongside police squads. Police forces in the affected cities also shared images of the raids on social media under the hashtag "#NullToleranz," or zero tolerance.

There are about 50 criminal clans active in NRW, with their collective membership topping 10,000, according to police information cited by the Rheinische Post newspaper.

The clans are often involved in prostitution, which is legal in Germany, but also commit acts of violence and vandalism, as well as welfare fraud and other non-violent crimes.

The police are currently investigating the clans' possible offenses in the real estate market, state criminal police representative Thomas Jungbluth told the newspaper.

'No tolerance for lawlessness'

The police force in the city of Essen said that some clan members show "little respect towards police or emergency services."

"We won't stand for it," they tweeted.

State Interior Minister Herbert Reul, who observed the raid in Bochum, said it was paramount that state authorities respond to clan criminality.

"We need to show that we are here and that we have no tolerance for lawlessness," he said. "We must not allow that criminal structures decide what the law is in Germany."

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