Fourteen people were injured and six arrested after police officers clashed with Catalan separatists in downtown Barcelona as tensions rose ahead of the first anniversary of the Spanish region’s referendum on secession.

At least one regional police officer was injured in the riot, according to Catalan authorities.

Violence erupted after separatists protested at a march of around 3,000 people, which was being held to demand that Spain’s nationwide police officers were paid as much as Catalan’s regional police.

The Catalan separatists were furious at the march being held so close to Monday’s anniversary of last year’s referendum on secession, which was held despite being banned by Spain’s top court.

The referendum was marred after national police and civil guard officers clashed with voters and injured hundreds of people.

A separatist tossed purple paint on a man at the march and other protesters then sprayed colourful powder at local police officers and charged police lines.

Some of the protestors also threw projectiles. Officers struck separatists with their batons as they held the crowd back from the march.

Protesters threw powder at officers (EPA)

Further confrontations took place when separatists tried to enter Barcelona’s main square, where the pro-police march had just finished.

Separatists shouted “Get out of here fascists!” at police supporters and cried for “independence”.

Those backing the police responded by shouting “we will be victorious” and “our cause is just!”

Many marchers, who oppose Catalonia’s independence, were carrying Spanish flags.

The march had originally been meant to end in another square, home to the regional and municipal governments’ seats, but around 6,000 separatists, according to police, gathered there to force protesters to change their route.

Ada Colau, the city’s mayor, was forced to issue a plea for civility as tensions rose once again.

Riot police covered in paint (AFP/Getty ) (AFP/Getty)

“I call for calm,” she said.

“This city has always defended that everyone can exercise their rights to free speech,” she told Catalunya Radio