About 450 officers have been searching several apartments, two companies' premises and six prison cells connected to the organisation called "Fussilet 33 e.V." since 6am local time (0500 GMT), police said in a statement.
Police said on Twitter that the organisation had now been banned. They have searched 24 properties and searches are ongoing, they said.
Man drives into crowd in German town, three people injured:police
Neither police nor the Berlin state's interior ministry were available to comment further when contacted by Reuters.
The federal prosecutor has said that Anis Amri, the Berlin attacker, visited a mosque run by the "Fussilet 33 e.V." organisation on the day of the December attack.
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