After a year in custody, the Catalan politicians accused of holding an illegal referendum and then unilaterally declaring independence have been charged with rebellion and misuse of public funds, for which they face up to 25 years in prison.

Friday’s decision to pursue the most serious charges laid against the accused puts paid to any hope that the socialist government’s more conciliatory stance might lead to any meaningful negotiation on the Catalan issue.

The imprisonment of the Catalan leaders was already a stumbling block to any talks and is widely regarded by all sides in Catalonia as excessive, unjust and politically motivated.

“The government has missed a golden opportunity to remove the Catalan conflict from the courts and put it back in the political arena, which is where it belongs,” the Catalan president, Quim Torra, said.

The prime minister, Pedro Sánchez, had “decided not to act, which amounts to complicity with repression”, Torra added.

María José Segarra, the fiscal general of Spain’s supreme court, formally charged Oriol Junqueras, the former Catalan vice-president, and eight ministers and senior officials with rebellion, and demanded a 25-year sentence for Junqueras and up to 17 years for the others.

Josep Lluís Trapero, the former head of the Mossos d’Esquadra, the Catalan police force, has also been charged with rebellion, as have three other senior officers, for failing in their duty to prevent the referendum from taking place. The fiscal has asked for an 11-year sentence for Trapero.

Carles Puigdemont, the former president, and five other senior officials who are in self-imposed exile in Belgium, Switzerland and Scotland, have not been included as they cannot be charged in absentia, although they face extradition on similar charges under a European order.

The former Catalan government ministers Joaquim Forn, Jordi Turull, Josep Rull, Raül Romeva and Dolors Bassa all face 16-year sentences. Jordi Sànchez and Jordi Cuixart, ex-leaders of the two main Catalan grassroots movements, and Carme Forcadell, a former speaker in the Catalan parliament, face 17 years as “promoters and leaders” of the rebellion.

Nine other government members face fines and sentences of up to seven years for misuse of public funds and disobedience.

The fiscal’s announcement comes a day after the state’s attorney, who represents the ministry of justice and therefore the government, brought reduced charges of sedition – essentially a public order offence – which carries a lighter sentence.

The move immediately drew opposition accusations of government interference. The justice minister, Dolores Delgado, rebutted the accusation that the state’s attorney had come under political pressure.

The trial is expected to be held early in the new year and the accused may end up being tried in parallel by the fiscal and the state’s attorney with both sedition and rebellion.

Junqueras said he and his fellow accused were victims of a political process and were braced for “a long prison sentence after an unfair trial”.

“I will face the court with my head held high and with the conviction that it could never be a crime to vote for the country that I love,” he said.