Carles Puigdemont's capture, aided by Spanish intelligence services, sparked protests of tens of thousands in Catalonia's main city of Barcelona and other towns in the wealthy northeastern corner of Spain. Some of the demonstrators clashed with riot police, leaving more than 50 civilians and police officers injured and leading to four arrests. Puigdemont will appear before a German judge on Monday.

Spain was plunged into its worst political crisis in four decades when Puigdemont's government flouted a court ban and held an ad-hoc referendum on independence for the northeastern region in October.

The Catalan parliament's subsequent declaration of independence received no international recognition and provoked a takeover of the regional government by Spanish authorities that they say won't be lifted until a new government that respects Spain's Constitution is in place.