Carles Puigdemont will remain in prison in Germany pending a decision on an extradition demand brought by Spain.
German authorities have 60 days to reach a decision on the request, which the former Catalan president opposes.
The district judge seemed to criticise the content of his arrest warrant during Monday’s hearing, saying acceptance was not a foregone conclusion.
Schleswig-Holstein state prosecutor Georg Guentge explained that no judgement had been made on extradition, simply that they were in a correct procedure. He said as the Attorney's General office they would analyse the admissibility of the demand but that the deciding court would be the Higher Court in Schleswig.
Puigdemont was arrested under the European arrest warrant on Sunday while travelling by car on his way to Brussels from Helsinki.
"He is very calm," said Paul Bekaert, Carles Puigdemont's Belgian lawyer. "I spoke to his Spanish lawyer who got him on the phone, he is very calm, very calm so for the moment we have no news."
Puigdemont has been living in self-imposed exile in Brussels since Catalonia’s unilateral declaration of independence last October.
Spain is seeking his extradition on charges of rebellion, sedition and misuse of public funds.