Police have taken a 27-year-old alleged Daesh supporter back into custody, investigators said on Friday, after having released him earlier.
The Muslim convert - whose name has not been published due to Germany's strict privacy laws - was first detained Wednesday in the eastern German state of Brandenburg over a feared terrorist attack but was released the next day when a raid turned up no evidence of a plot.
No further details on the stage of the investigation however were available.
Police had previously said they believed the man, a German national, was a sympathizer of the extremist group Daesh after a search of his apartment turned up a weapon, military-style equipment and Daesh material.
Security sources told dpa earlier in the week that the man had possibly been planning to attack a festival in Eisenhuettenstadt, a town near the Polish border, with explosives later this month.
A 30-year-old acquaintance of the man, who was detained on Thursday, remains in custody, police said.
That man, who is also a Muslim convert from Eisenhuettenstadt, was suspected of planning a bomb attack, police said. His name has also not been released.
German officials are on high alert at the moment about extremism following two Islamic State-inspired attacks in the country last month.
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