German security agencies held emergency talks after U.S. intelligence warned that Islamic extremists might be planning an attack in Germany, the federal crime office said.
The most likely target is considered to be part of the public transport system.
A spokeswoman for the German crime authorities could not confirm a report in the news magazine Focus on Saturday that Islamic extremists planned an attack this weekend in Germany to coincide with Eid, the religious festival that marks the end of the Muslim fasting month of Ramadan.
"A foreign security agency has informed the federal crime office of its suspicions which require increased vigilance. We can't give any more details because of ongoing investigations," the BKA spokeswoman said.
She said regional and federal police had met in Meckenheim near Bonn to discuss the situation. Citing a document issued to the German chancellery and the foreign ministry, Focus reported that a group of three men had been given an order on December 12 to carry out an attack in Germany on part of the public transport system.