The Spanish Supreme Court charged the former President of Catalonia, Carles Puigdemont, and 12 others, backers of the Spanish region’s secession with the crime of rebellion on Friday.
The move brings Puigdemont, who has fled to Belgium and his allies, one step closer to a trial in which they would face up to 30 years’ imprisonment, if convicted.
The ruling also covered Puigdemont’s former deputy, Oriol Junqueras; pro-independence civil society campaigners, Jordi Sanchez and Jordi Cuixart and former Catalan interior minister, Joaquim Forn.
The four have been in pre-trial detention for months.
Other indicted include: the former speaker of the Catalan parliament, Carme Forcadell and Marta Rovira of the far-left ERC party, who dodged a court summons and announced she was going into exile.
Later Friday, the Spanish Supreme Court was due to decide whether a separatist candidate for the presidency of the Catalan parliament, Jordi Turull, should also be placed in pre-trial detention.
Catalonia is at the centre of an unprecedented constitutional crisis for Spain.
Puigdemont was deposed by the Madrid government after organising an illegal referendum on independence in which more than 90 per cent of votes were cast in favour of a break-up from Spain.
However, pro-Union Catalans mostly boycotted the ballot, and turnout was less than 50 per cent.
The Spanish government called new regional elections in December, in which secessionist parties won again.
Since then, the Spanish region has been in a state of political limbo.