Catalonia's sacked vice president and three other separatist leaders will remain in prison pending a probe over their role in the region's independence drive, a Supreme Court judge decided Monday.

Oriol Junqueras, who was sacked as vice-president when the Catalan parliament declared independence on October 27, Joaquim Forn, who used to be in charge of interior matters in Catalonia, and the leaders of two pro-independence associations will stay in prison, the court said in a statement. Six other former ministers who were also remanded in custody will be released on bail.