German prosecutors on Tuesday asked a court to order the extradition to Spain of Catalonia's ousted president Carles Puigdemont on a rebellion charge following his arrest in Germany last month.
The request comes after demonstrations by independence supporters at the weekend in Berlin and Catalonia calling for Puigdemont's immediate release.
"The prosecutor's office of Schleswig-Holstein state applied for an extradition arrest warrant against former Catalonian regional president Carles Puigdemont from the superior regional court," it said in a statement.
It was not immediately clear when the court would rule on Puigdemont's possible extradition.
Puigdemont was arrested by German police on March 25 as he was travelling from Finland back to Belgium, where he has been living in self-imposed exile since Catalonia's failed independence bid last October.
The detention came two days after a Spanish judge issued European arrest warrants for Puigdemont and other fugitive separatist leaders.
They have been ordered to stand trial for rebellion, misuse of public funds and disobeying the state for organising last year's referendum on Catalan independence, which Madrid deemed illegal.
Puigdemont's arrest has sent tensions soaring at home, triggering a wave of protests in the wealthy northeastern Spanish region.
A lower court in Germany had already ordered Puigdemont to remain in custody in the northern town of Neumuenster as judicial authorities mull Spain's request for him to be handed over.
They have 60 days to make a decision.
German media say the request has been complicated by the fact that rebellion, which carries a maximum penalty of 30 years in jail in Spain, is not a crime under German law.
However, the prosecutor's office said that "after intensive review" it concluded that the rebellion charge "contains in essence the accusation of calling an unconstitutional referendum despite violent riots that could be expected," hence matching the German charge of "treason".
"Word-for-word conformance between the German and Spanish criminal codes is thus not legally required," it said.
Puigdemont's lawyer Jaume Alonso-Cuevillas said he would have been surprised if German prosecutors had not pressed for extradition and that his client's fate now rested with the courts.
"This case is extraordinary for its importance, its political implications and all the infringements of basic rights that we will prove have been committed by the Spanish state," he told Catalonia's Rac1 radio, calling Puigdemont a "political prisoner".
The superior regional court confirmed it had received the request, adding that it was "undetermined when a decision on the application can be expected".
The higher court must first decide if there is a legal basis to put Puigdemont in pre-extradition custody by reviewing the written request from Spain. It will then rule on the extradition bid itself.
Puigdemont can appeal an order of extradition to a German federal court, a course his lawyers have said they will pursue.