Catalonia has provoked furious responses not just from the Spanish central government, but also from EU officials following its unilateral declaration of independence.
The independence of the wealthy region would pose an unprecedented threat to the EU far worse than that of Brexit, in large part because of its eurozone membership.
According to the BBC’s economic correspondent, a crackdown on Catalan independence would be welcomed by eurozone states since the future of the single currency depends on it.
Kamal Ahmed told Radio 4 Today: “Markets are quiet at the moment, but they will now determine whether this political crisis turns into an economic crisis.
“Catalonia is a big economy, its GDP is £196billion a year, it has a bigger economy than Portugal.

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“This is worse than Brexit, simply because there is absolutely no rulebook for a country leaving the eurozone, not just the EU.”
He explained that if Catalonia were to go it alone, as an independent state, the long-term “grand plans” of Jean-Claude Juncker and those in Brussels would be thrown into peril.
Mr Ahmed claimed that a dramatic departure from the EU would leave the bloc scrambling to fill a “massive” budget hole.
Mr Ahmed added: “The independence of Catalonia would incredibly fundamental. Absolutely catastrophic.
“The EU and Spain would desperately try to contain that risk, both economic and political.
“This would be an existential threat to the eurozone and long-term EU projects.
“Catalonia is a net contributor to the eurozone, like Britain is, so that would leave a massive hole in the budget.”