Pro-independence groups and trade unions in Catalonia have called for a general strike to take place on 3 October after Spain's constitutional court declared the independence referendum vote illegal and more than 800 people were injured in violent clashes with riot police.

Preliminary results indicated that 90% of the estimated 2.26 million people who cast their ballot had voted 'yes.' The turnout was around 42%, despite a police operation aimed at preventing hundreds of people from voting.

The Catalan government said more than 840 people received medical attention on Sunday (1 October) after voters clashed with riot police at polling stations.

After the police crackdown, two of Spain's biggest unions, the UGT and CCOO, and Catalan's independence association (ANC), along with 41 other organisations called for a region-wide strike.

"We call all society, on employers' organisations, business owners, unions, workers, self-employed workers, institutions and all the citizens of Catalonia to stop the 'country' on Tuesday, October 3," they said in a statement, quoted by Spanish newspaper La Vanguardia.

Tourism and production in Catalonia fuel the Spanish economy, with the region's economic output totalling a fifth of Spain's GDP.

Spain's Prime Minister Mariano Rajoy is facing a constitutional crisis following the violent secession vote. He is set to meet with the opposition leader, socialist politician Pedro Sanchez, on Monday (2 October) as Catalan's regional leader, Carlos Puigdemont, holds an emergency meeting with his government.