Spanish government officials have confirmed that ousted Catalan leader Carles Puigdemont has travelled to Brussels.

Puigdemont's move comes just one day after hundreds of thousands of Catalans took to the streets of Barcelona to voice their opposition to the region's declaration of independence.

There is now vast political uncertainty for the region after Catalonia's political leadership was fired on Saturday by central authorities in Madrid who are facing the worst political crisis Spain has seen in decades.

In response to the secessionist vote, Spanish Prime Minister Mariano Rajoy triggered unprecedented constitutional powers.

He fired Catalonia's secessionist regional government and called an early regional election for December 21.

Today is the first working day since the region declared independence and its leadership was fired.

Earlier this week, a Belgian migration minister said granting Catalan leader Carles Puigdemont political asylum in Belgium would be "not unrealistic" if he asks for it.

While there was no indication Puigdemont was hoping to go to Belgium at the time, the country is one of few members of the European Union where EU citizens can ask for political asylum.

"It is not unrealistic if you look at the situation," Belgium's migration minister, Theo Francken, told Belgian broadcaster VTM.

"They are already talking about a prison sentence," Francken, a member of Flemish nationalist party N-VA, said. "The question is to what extent he would get a fair trial."

It would be difficult for Spain to extradite Puigdemont in such a case, he said.

PA Media