As another day passed with no sign of dialogue and pro-independence parties pushed for the declaration of a Catalan Republic as early as Monday, Gunther Oettinger, the budget commissioner, urged the two sides to talk.
"The situation is very, very disturbing. A civil war is planned in the middle of Europe," Mr Oettinger said in Munich.
"One can only hope that a conversation will be made between Madrid and Barcelona soon," he continued, adding that the EU could only mediate talks "if asked".
As nerves grew that an independence declaration could be about to plunge Catalonia into the unknown, Banco Sabadell, the fifth-largest banking group in Spain, announced it was moving its headquarters to Alicante.
CaixaBank too was looking at options, the Spanish daily El Mundo reported, including a relocation to the Balearic Islands if an independence declaration tipped Catalonia into a state of legal chaos. The insurer Catalan Occidente also said it was ready to take "all necessary decisions" as "events developed".