European Commission President Jean Claude Juncker said today he did not want Catalonia to become independent, because that would encourage other regions to do the same, making the European Union ungovernable.

"If we allow Catalonia - and it is not our business - to separate, others will do the same. I do not want that," Jean Claude Juncker said in a speech at Luxembourg University.

"I wouldn't like a European Union in 15 years that consists of some 98 states," he continued. "It's already relatively difficult with 28 and with 27 not easier, but with 98 it would simply be impossible."

The EU's statistics agency Eurostat lists the bloc as consisting of 98 major regions.

Juncker said he was "very worried" about separatist tendencies in Europe and had encouraged Spanish Prime Minister Mariano Rajoy to ensure the situation did not get out of control.

Referring to Catalan calls for EU mediation, he said the Commission could not mediate if only one side asked it to do so. The EU has said it has confidence in Rajoy to resolve what it sees as an internal issue.

"If the Commission or European Council President (Donald) Tusk were to get involved with only one party asking for mediation, this would lead to a great rejection of the European Union," Juncker said.