Catalan officials claimed 90% of 2.2million voters had called for independence in an ‘illegal’ referendum blighted by violent scenes which left at least 888 people injured.
World leaders condemned the brutal scenes after officials revealed that hundreds of protesters have been injured so far.
Officers were seen kicking and stamping on protesters as they stormed buildings and seized ballot boxes.
Footage captured in the village of Sarria de Ter in the province of Girona showed authorities using an axe to smash down the doors of a polling station where Catalan president Carles Puigdemont was due to cast his vote.
He said the region had won the right to become an independent state with the referendum results due in a few days.
And in Barcelona, the region’s capital, officers fired rubber bullets at thousands of protesters demonstrating against their votes being denied.
Boris Johnson condemned the violent clashes but said that the UK saw the vote as unconstitutional.
The Foreign Secretary said: ‘We are obviously worried by any violence but clearly the referendum, as I understand it, is not constitutional so a balance needs to be struck. We hope very much that things will calm down.
Labour leader Jeremy Corbyn earlier called on Theresa May to intervene with the Spanish government over the police crackdown.
Mr Corbyn condemned the ‘shocking police violence’ being used as he tweeted: ‘I urge Theresa May to appeal directly to Rajoy to end police violence in Catalonia & find political solution to this constitutional crisis.’
Pope Francis also urged Europeans not to fear unity and to put aside nationalistic and other self-interests during a speech in Bologna in Italy.
He did not mention the police violence during Catalonia’s independence referendum – but in a speech to university students, he recalled that the European Union was borne out of the ashes of war to guarantee peace.
He warned that conflicts and other interests were now threatening those founding ideals.
Francis said: ‘Don’t be afraid of unity! May special interests and nationalism not render the courageous dreams of the founders of the European Union in vain.’
Scotland’s first minister Nicola Sturgeon – who has campaigned for independence for Scotland – tweeted: ‘Some of the scenes in Catalonia are quite shocking and surely unnecessary. Just let people vote.’
European leaders also voiced their disquiet over the degree of violence used, and called for dialogue between regional and national leaders.
Belgian prime minister Charles Michel tweeted: ‘Violence can never be the answer. We condemn all forms of violence and reaffirm our call for political dialogue.’