MADRID/BARCELONA (Reuters) - Twelve Catalan politicians go on trial on Tuesday for their role in Catalonia’s failed 2017 independence bid, putting the spotlight back on Spain’s biggest political crisis in decades which could make it flare once again.

Police vans, believed to carry Catalan separatist politicians, leave prison on their to way to the Supreme Court in Soto del Real, Spain, February 12, 2019. REUTERS/Juan Medina

To the dismay of much of the rest of Spain, Catalonia defied a judicial ban by carrying out a referendum and subsequently unilaterally declaring independence in October 2017.

There was shock at home and abroad when police used batons and rubber bullets on protesters on the day of the vote. Some of the Catalan separatist leaders were later arrested or fled the country.

The start on Tuesday of the trial will refocus attention on the region’s push for secession which so rattles Spain’s political and cultural identity.

The trial will decide if Catalan nationalist leaders stay in jail. The public prosecutor is seeking prison terms of up to 25 years on charges of rebellion and misuse of public funds. At stake are Spain’s stability, the future of Catalonia’s independence movement as well as the region’s and the central government’s image abroad.

“It’s the most important trial we have had in democracy”, Supreme Court president Carlos Lesmes told reporters on Feb. 1, referring to the return to democracy in Spain after dictator Francisco Franco’s death in 1975.

Raul Romeva, one of nine defendants jailed without bail since late 2017 facing the charge of rebellion, has made clear his view that it should end only with an acquittal.

“A (prison) sentence would weigh forever on history and on Spain’s future,” Romeva told Reuters in an interview conducted by email from jail.

At the time of his arrest, Romeva was foreign minister in Catalonia’s regional government and a member of the European Parliament.

Fellow defendants include veteran Catalan politicians Oriol Junqueras and Carme Forcadell. Notably absent from the list is former Catalan president Carles Puigdemont, who is in self-imposed exile in Belgium and thus cannot be tried in Spain.

The dozen’s fate has been a rallying cry for separatists ever since 2017, said Federico Santi, analyst at political risk consultancy Eurasia, adding that he expected, like other observers, that the trial will re-ignite tensions.

Pro-Catalan independence protests had quieted down over the past months but separatist groups have called a series of protests in Catalonia and in Madrid to coincide with the trial.

Their supporters say they are political prisoners, while Madrid accuses them of breaking the law.

Among the many witnesses will be Mariano Rajoy, who was Spanish prime minister at the time of the independence vote and its aftermath.

RIFT

Lluis Orriols, a political science professor at Universidad Carlos III in Madrid, thinks the trial will reinvigorate the separatist debate ahead of end-May local and regional elections.

“The Catalan question is activating a nationalistic and identitarian confrontation not only in Catalonia but also in all of Spain,” Orriols said.

The trial starts as the Socialist government, which controls less than a quarter of seats in parliament, faces a key vote on the 2019 budget on Wednesday. A failure to approve the budget proposal could prompt a snap parliamentary election this year.

Socialist Prime Minister Pedro Sanchez relies on smaller parties, and in particular Catalan nationalists, to get the budget adopted. These have said they would block the bill, citing their dissatisfaction with Sanchez’s policy towards the region, despite his efforts for dialogue..

On the other hand, Spain’s right-wing parties accuse Sanchez of being too soft with Catalan separatists. On Sunday, thousands gathered in Madrid to protest Sanchez’ Catalan policies.

In Catalonia, support for the twelve is not unanimous. The population is largely split in two between those who favor remaining part of Spain and those wanting to secede.

After imposing direct rule on Catalonia in October 2017, Madrid called fresh regional elections that December in a bid to curb the independence movement. But the move backfired and the secessionists retained a slim majority in the Catalan assembly.

The last time a trial for rebellion was held in Spain was in 1982 after a failed military coup attempt. Its leader, found guilty of rebellion by a military court, was sentenced to 30 years of prison.