Catalonia's regional government has said the number of people injured in the polling day violence has risen to 844 after police fired rubber bullets and beat people trying to vote.

The Spanish Civil Guard was seen hitting people with batons, fired rubber bullets into crowds and forcibly removed would-be voters from polling stations in actions that were condemned internationally but were described by the government as "proportionate".

The referendum, declared illegal by Spain's central government, has thrown the country into its worst constitutional crisis in decades and deepened a centuries-old rift between Madrid and Barcelona.

Catalonia has agitated for greater independence for centuries but the secession campaign received new impetus during the financial crisis when the wealthy region came to feel it was supporting the rest of the country.

The autonomous Catalan government first held a non-binding referendum in 2014 on independence in which 80 per cent expressed support.

This fresh vote was called in June this year with a separate law passed by the Catalan parliament which said the referendum would be binding based on a simple majority without a minimum threshold.

Opposition parties in Barcelona protested against the law and have called on supporters to boycott the vote.

The national government called the move a “constitutional and democratic atrocity” and said it was invalid because it did not have the support of two thirds of the Catalan parliament – the threshold needed to pass laws on constitutional matters.

Last month, the Constitutional Court in Madrid ruled that the referendum was illegal because it violated a clause in the constitution which refers to "the indissoluble unity of the Spanish nation, the common and indivisible homeland of all Spaniards".

Catalonia independence referendum: Riot police clash with voters Show all 17 1 /17 Catalonia independence referendum: Riot police clash with voters Catalonia independence referendum: Riot police clash with voters A man faces off Spanish Civil Guards outside a polling station in Sant Julia de Ramis Reuters Catalonia independence referendum: Riot police clash with voters Riot police form a security cordon around the Ramon Llull school in Barcelona EPA Catalonia independence referendum: Riot police clash with voters Riot police evict a young woman during clashes between people gathered outside the Ramon Llull school in Barcelona EPA Catalonia independence referendum: Riot police clash with voters Spanish Civil Guard officers break through a door at a polling station in Sant Julia de Ramis Reuters Catalonia independence referendum: Riot police clash with voters Spanish National Police clash with pro-referendum supporters in Barcelona on Sunday AP Catalonia independence referendum: Riot police clash with voters Crowds raise their arms up as police move in on members of the public gathered outside to prevent them from voting in the referendum at a polling station where the President Carles Puigdemunt will vote later today Getty Catalonia independence referendum: Riot police clash with voters People confront Spanish Civil Guard officers outside a polling station Reuters Catalonia independence referendum: Riot police clash with voters Three man hold each other as they try to block a Spanish police van from approaching a polling station AP Catalonia independence referendum: Riot police clash with voters A woman shows a ballot to a Spanish Civil Guard officer outside a polling station Reuters Catalonia independence referendum: Riot police clash with voters A man wearing a shirt with an Estelada (Catalan separatist flag) and holding carnations faces off with a Spanish Civil Guard officer Reuters Catalonia independence referendum: Riot police clash with voters Police try to control the area as people attempt to cast their ballot at a polling station in Barcelona Getty Catalonia independence referendum: Riot police clash with voters A man is grabbed by officers as police move in on the crowds Catalonia independence referendum: Riot police clash with voters Two women argue with a Spanish National policeman during clashes between Catalan pro-independence people and police forces at the Sant Julia de Ramis sports centre in Girona EPA Catalonia independence referendum: Riot police clash with voters Sant Julia De Ramis in Spain Getty Catalonia independence referendum: Riot police clash with voters Confrontation outside a polling station in Barcelona, where police have tried to stop people voting AFP/Getty Images Catalonia independence referendum: Riot police clash with voters A Spanish National Police officer aims a rubber-bullet rifle at pro-referendum supporters in Barcelona AP Catalonia independence referendum: Riot police clash with voters Riot police clashed with voters as polls opened in Barcelona Sky News

The Catalan government says Spain is "the shame of Europe" for the way it has cracked down on the region's bid to hold a secession referendum

Government spokesman Jordi Turull says "what the police are doing is simply savage, it's an international scandal."

Barcelona’s mayor, Ada Colau, has called on Spanish Prime Minister Mariano Rajoy to resign over the violence.

She told TV3 that "Rajoy has been a coward, hiding behind the prosecutors and courts. Today he crossed all the red lines with the police actions against normal people, old people, families who were defending their fundamental rights."

She adds that "It seems obvious to me that Mariano Rajoy should resign."

Several international commentators, including former Greek finance minister Yanis Varoufakis, have echoed a comment made by Catalan President Carles Puigdemont comparing Mr Rajoy’s conduct to General Francisco Franco who brutally surprised Catalonia at the end of the Spanish Civil War in 1939.

But Mr Rajoy has remained defiant saying “there was no independence referendum today”.

In an address to television cameras, he said the people of Catalonia had been tricked into taking part in the illegal vote.

A protester is grabbed by the Civil Guard in the village of Sant Julia de Ramis where the Catalan President was due to vote (AFP/Getty Images)

He accused the regional government of using the referendum as a strategy against legality and democratic harmony and was a “path that leads to nowhere”.

He praised the Civil Guard and the security services for upholding the law.

The government had hoped to avoid the vote fearing it would cause a constitutional crisis but has caused one regardless by its heavy-handed response.

Solidarity demonstrations have already taken place in other Spanish cities such as Seville and trade union officials in Catalonia have called for a general strike.