Puigdemont "was arrested today at 11:19 am by Schleswig-Holstein's highway patrol force," a German police spokesman told AFP, adding that the detention was based on a European warrant.
"He is now in police custody", added the spokesman.
Puigdemont's party spokeswoman Anna Grabalosa also separately confirmed that he was detained on arrival in Germany from Denmark.
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"It happened as he crossed the Danish-German border. He was treated well and all his lawyers are there. That is all I can say," she said.
Puigdemont is wanted by Spain on charges of "rebellion" and "sedition", over his independence bid for Catalan.
He had been visiting Finland since Thursday, but slipped out of the Nordic country before Finnish police could detain him.
Puigdemont's lawyer Jaume Alonso-Cuevillas, said on Twitter that Puigdemont was picked up by German police as he was travelling back to Belgium where he has been living in self-imposed exile.
