Protesters who are backing Catalonia’s secession from Spain have blocked major highways, train tracks and roads across the northeastern region.

A 24-hour general strike organised by small unions of pro-independence workers and students is underway to protest the trial of a dozen separatist leaders.

On paper, the strike is demanding improved social policies, including a 35-hour work week and a higher minimum wage, but protesters carried pro-secession flags and chanted slogans for the release of the 12 separatists currently on trial in the Madrid-based Supreme Court of Spain.

Strikers formed human chains to stop traffic on several highways across Catalonia, it has been reported.

There have also been some reports of clashes, with one protester arrested for hitting an officer in downtown Barcelona, police said.

Strikers light fires and clash with police in Catalonia Show all 11 1 /11 Strikers light fires and clash with police in Catalonia Strikers light fires and clash with police in Catalonia Police officers work to remove burning tires that were placed in the road by demonstrators during Catalonia's General Strike AP Strikers light fires and clash with police in Catalonia Police officers work to remove burning tires that were placed in the road by demonstrators during Catalonia's General Strike AP Strikers light fires and clash with police in Catalonia Police officers remove demonstrators who are blocking a road in Barcelona during Catalonia's General Strike AP Strikers light fires and clash with police in Catalonia Police officers remove demonstrators who are blocking a road in Barcelona during Catalonia's General Strike AP Strikers light fires and clash with police in Catalonia Police officers remove demonstrators who are blocking a road in Barcelona during Catalonia's General Strike AP Strikers light fires and clash with police in Catalonia Graffiti reads 'February 21st National Strike' during the Catalan general strike EPA Strikers light fires and clash with police in Catalonia Police officers remove demonstrators who are blocking a road in Barcelona during Catalonia's General Strike AP Strikers light fires and clash with police in Catalonia Police officers remove demonstrators who are blocking a road in Barcelona during Catalonia's General Strike AP Strikers light fires and clash with police in Catalonia Police officers remove demonstrators who are blocking a road in Barcelona during Catalonia's General Strike AP Strikers light fires and clash with police in Catalonia Police officers remove demonstrators who are blocking a road in Barcelona during Catalonia's General Strike AP Strikers light fires and clash with police in Catalonia Police officers work to remove burning tires that were placed in the road by demonstrators during Catalonia's General Strike Reuters

Strikers, many of whom covered their faces, threw objects at a police line in a standoff on a rural highway before agents in riot gear advanced to disperse them.

Protesters elsewhere burned tyres on some highways. The main unions in Catalonia did not back the strike.

In Barcelona, students and the pro-secession group ANC were planning separate marches later on Thursday.

ANC’s protest slogan is “self-determination is not a crime”. The Spanish government says regions cannot independently secede, according to the constitution.

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The trial into the roles played by the 12 separatists in Catalonia’s failed 2017 secession attempt is in its second week.

Former Catalan government member Santi Vila and activists Jordi Sanchez and Jordi Cuixart are scheduled to testify at the court on 21 February. The trial is expected to last for at least three months.

Election results and polls indicate Catalonia’s 7.5 million residents are equally divided over the secession issue.