Catalonia's regional leader sought to call the European Union's bluff on Wednesday over a rising tide of national fragmentation and secessionism within the EU, demanding to know what Brussels will do if some of the union's member states splinter for the first time in EU history.

Increasingly at odds with Madrid over the legality of his drive to secure a mandate for a Catalan independence referendum, Artur Mas, the liberal nationalist prime minister of Catalonia who has called early elections for later this month in a bid to obtain that mandate, insisted that if a new country emerged from the Spanish turmoil a separate Catalonia would be entitled to remain a member of the EU inside the euro single currency zone.

"The big umbrella is the European Union … within Europe we can have a different political status," Mas said.

He came to Brussels to try to sway minds on Catalan secessionism and to demand answers to the pressing questions being thrown up by the prospect of the emergence of new states within the EU.

It has been a promising few weeks for independence movements, with the three-year euro crisis fomenting an upsurge in fragmentation within the 27-member union and within some of its bigger countries.

In September hundreds of thousands of Catalans took to the streets of Barcelona demanding home rule within the EU. The Scottish and British prime ministers reached a pact on the terms for a Scottish independence referendum in 2014. Last month in regional elections the Flemish separatist leader, Bart de Wever, gained control of Antwerp, the Flemish capital, Belgium's second city and the EU's second biggest port, gaining a bridgehead on his campaign for a country called Flanders.

Senior figures in Brussels have dismissed talk of automatic EU membership for breakaway "countries" in what looks like a failing effort to discourage secessionism. But the EU has never had to deal with the break-up of a member state. The Catalan, Scottish, and Flemish developments are sending the EU into uncharted territory, legally and politically. Mas threw down the gauntlet to EU policymakers.

"The will of the Catalan people is to continue joining the European Union and the euro," he said. "The question will be when that happens in the future is the European Union prepared to offer solutions to countries like Catalonia? The only thing they want is to change their political status."

On a parallel visit to Brussels a few months ago Nicola Sturgeon, the SNP's deputy first minister, bluntly asserted that an independent Scotland would automatically inherit all the rights, entitlements, and obligations of EU membership. It was a contentious statement which appeared unfounded. The issue remains unsettled.

Mas, by contrast, admitted the question had not been answered, but demanded a coherent response from EU policy-makers. "The European treaties do not say Catalonia can stay in the EU, but they don't say the opposite either," he stated.

Speaking on the eve of the campaign opening for the Catalan elections on 25 November, Mas also appeared to be attempting to drive a wedge between Madrid and Brussels, arguing that the EU could be forced to choose between the declared will of Catalans voiced freely and democratically first in an election and then in a referendum and the central government in Madrid seeking to outlaw those verdicts under the Spanish constitution.

Mas said that in the election this month Catalans knew they were voting on whether an independence referendum should be staged. If he and other separatist parties secured a strong mandate, the "consultation" – his term for a referendum – would be held within the new Catalan parliament's four-year term.

He would seek a deal with Madrid but would also pass new enabling Catalan legislation if Madrid ruled a referendum unconstitutional.

"The European Union has to take into account that the consultation will take place," he said. "If the Spanish state is completely against a consultation, then the European Union will support the democratic will of the Catalan people … our first objective is to reach an agreement with the central government to organise the consultation in the next four years. It seems that to reach agreement with the central government will be, let's say, a little bit difficult. Of course, we have always said that our aim is to make the consultation within the framework of the law - if we can, of Spanish law."

If that proved impossible, "then we are going to try to make this in the framework of a Catalan law, a specific Catalan law for consultations."