The president of La Liga said Tuesday that Catalan clubs like Barcelona and Espanyol would be excluded from Spain's top tier should the region succeed in its push for independence from Spain.
Javier Tebas said the country's sports law entitles only one non-Spanish territory - Andorra - to legally participate in the league or other official competitions.
The pro-independence government of Catalonia is pushing for a referendum to see how many of the wealthy northeastern region's inhabitants would like to secede.
The plan is overwhelmingly opposed by Spain's parliament, where the government of Prime Minister Mariano Rajoy has a large majority.
A debate held in parliament in April vetoed the region's request to hold a referendum by 299 votes against to 47 in favour.
Despite the veto, the Catalan government says it will hold a non-binding referendum on November 9, a decision that has led to furious arguments about the ballot's legality.
The government argues that such a move would violate the Spanish Constitution's stipulation that only the national government can call referendums on sovereignty and that all Spaniards are entitled to vote in such a ballot.
Whatever the outcome, the fact that Andorra - a tiny state straddling the Pyrenees Mountains that separate Spain from France - is allowed to play in the league creates a precedent that could permit the Catalan clubs' eventual inclusion.
Tebas said that for clubs from an independent Catalonia to be included in La Liga would require "a modification of the law" that would have to be approved by parliament.
"For such a modification to be given the go-ahead, we'd have to wait and see if the affected sector would agree to such a change," Tebas said, referring to the likely reaction in the rest of Spain to any secession by Catalonia.
Separatist sentiment has surged in Catalonia in recent years following Spain's refusal to give the region more autonomy and fiscal powers.
The push is Europe's latest secession attempt following a Scottish independence poll last month on separating from Britain which resulted in a No vote.
Catalonia, with some 7.5 million inhabitants, is Spain's wealthiest region. Barcelona vies with Real Madrid for supremacy on the football field - domestically and internationally - with both clubs being listed among the world's richest.
Tebas said the financial consequences of a split in La Liga caused by a Catalan secession would be "a disaster to the development of the football industry."