Gerard Pique broke down in tears describing Barcelona's 3-0 win over Las Palmas in an empty stadium as the "worst professional experience" of his life on a chaotic Sunday in Catalonia.

More than 500 people were injured as Spanish riot police fired rubber bullets and forced their way into activist-held polling stations over an independence referendum for the north-eastern region of Spain deemed illegal by the Spanish government.

After Barcelona's attempt to have their game abandoned was dismissed by Spanish league authorities, Barca decided to play behind closed doors in protest at the violent scenes.

"The board tried to cancel the game but it wasn't possible. They came down to speak to the players and we opted to play," Pique told reporters.

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"It was very difficult to play the game. It was the worst professional experience I have had in my life.

"We have had seven years of demonstrations without violence and what happened today has been seen around the world."

Pique has been an outspoken supporter of Catalonia's right to self-determination in the face of the Spanish government's crackdown on preparations for the referendum.

He posted a picture on his Twitter account as he voted before the game on Sunday.

And he believes the shocking scenes have only served to rupture fractious relations between Catalonia and Madrid even further.

"For a moment I couldn't believe it. I thought they would try to block the vote but they would try to do it in a peaceful manner," he added.

"It wasn't like that, but at least the whole world has seen it. This decision has made things a lot worse. It is one of the worst decisions made by this country in 40 or 50 years.

"It has only served to separate Catalonia and Spain more and it will have consequences."

Pique's political stance has seen him targeted by Spain fans when playing for the national team, despite his role in winning the 2010 World Cup and Euro 2012 with La Roja.

The 30-year-old has already announced his decision to retire from international football after the 2018 World Cup.

However, he said he will step aside before then if his presence in the Spain camp is deemed a problem by coach Julien Lopetegui or the federation.

"I think I can continue going with the national team because I truly believe there are many people in Spain totally against the events that took place today in Catalonia and that believe in democracy," said Pique.

"If not, I will not go. If anyone in the federation thinks I am a problem I don't have a problem in stepping aside and retiring from international football before 2018."