Catalan police officers clash with demonstrators outside a subway after blocking a train rail, during a general strike in Catalonia, Spain, Feb. 21, 2019.
Catalan police officers clash with demonstrators outside a subway after blocking a train rail, during a general strike in Catalonia, Spain, Feb. 21, 2019.

BARCELONA, SPAIN - Protesters backing Catalonia's secession from Spain clashed with police and blocked major roads and train tracks across the northeastern region on Thursday during a strike called to protest the trial of a dozen separatist leaders.

Regional police say they made four arrests when they met resistance trying to clear groups of protesters who had stopped traffic. The regional emergency service said that 22 people had been treated for minor injuries.
 
Twelve officers were also injured in the clashes, according to police. Protesters threw rocks at police lines and burned tires on some highways.
 
Regional transportation authorities said the disruptions affected main thoroughfares in Barcelona and half a dozen major highways and railway tracks elsewhere in Catalonia.
 
The general strike was organized by small unions of pro-independence workers and students. On paper, they were demanding improved social policies, including a 35-hour work week and a higher minimum wage, but the protesters carried pro-secession flags and chanted slogans for the release of the 12 separatists currently on trial in the Madrid-based Supreme Court.
 
The main unions in Catalonia did not back the strike, which appeared to have a limited impact on businesses.
 
In Barcelona, students in favor of secession held a mid-day march attended by 13,000 people according to the city's urban police. The pro-secession grassroots group ANC — whose protest slogan is ``self-determination is not a crime'' — was planning a separate march later Thursday.
 
The Spanish government says regions cannot independently secede, according to the Constitution.
 
The trial into the roles played by the 12 separatists in Catalonia's failed 2017 secession attempt is in its second week. On Thursday, former Catalan government member Santi Vila, ANC's ex-president Jordi Sanchez and fellow activist Jordi Cuixart were scheduled to testify at the court. The trial is expected to last at least three months.
 
Election results and polls indicate that Catalonia's 7.5 million residents are divided down the middle over the secession issue.