Former Ukip leader Nigel Farage said a vote by Catalonia for independence was Brussels’s “worst nightmare”.
He added: “This makes Brexit look like a Sunday afternoon picnic.”
Catalan MPs yesterday overwhelmingly agreed to break away from Madrid.
Then, as thousands of supporters took to the streets, Spain’s national parliament immediately acted to impose direct rule.
The prospect of future violent clashes between Spanish security forces and the Catalans sent a shiver through Europe.
European Commission chief Jean-Claude Juncker admitted the EU was facing a threat to its existence.
The EU “doesn’t need any more cracks, more splits”, he said.
But Brexiteer Mr Farage said the EU was partly responsible for the crisis by backing the Madrid government.
The former Ukip leader said “This is Jean-Claude Juncker’s worst nightmare.The European Union backed Spanish brutality and turned the Catalans against the EU. This makes Brexit look like a Sunday afternoon picnic.”
The crisis began less than a month ago when a referendum backed independence, despite violence at the polls as Spanish national police tried to stop it taking place.
The Catalan parliament in Barcelona voted by 70 to 10 yesterday to split from Madrid as a result.
Within an hour the upper house of the national parliament voted to give Spanish Prime Minister Mariano Rajoy the authority to impose direct rule And last night Mr Rajoy dissolved the Catalan parliament and called a snap regional election on December 21.
He also said he had decided to sack the Catalan government and its police chief. Independence supporters in Catalonia, one of Spain’s wealthiest regions, urged civil servants to disobey orders from Madrid and called for “peaceful resistance”.
In London, Theresa May was among the first to come out in support of Mr Rajoy.
A Downing Street spokesman said: “The UK does not and will not recognise the unilateral declaration of independence made by the Catalan regional parliament.
“It is based on a vote that was declared illegal by the Spanish courts. We continue to want to see the rule of law upheld, the Spanish constitution respected, and Spanish unity preserved.”
The US, Germany and France also voiced their backing for Spanish unity. Donald Tusk, president of the European Council, said the EU would only deal with the central government in Madrid.
But outside the Catalan parliament in Barcelona’s Ciutadella Park, a crowd of more than 2,000 independence supporters defiantly shouted “Liberty” and sang traditional songs.
Catalan leader Carles Puigdemont declared Catalonia was now “an independent, sovereign and social democratic state”.