Barcelona's future in the La Liga is in the balance as Catalans voted in favour of independence from Spain.
Parties vowing a referendum on self-rule for Catalonia won massive backing in regional elections on Sunday.
Barcelona would be able to choose between playing in La Liga or Ligue 1, according to Xavier Trias, the local mayor.
"We (Catalunya) do not have the possibility of a competitive league," he was quoted as saying by AFP.
"We would have very few teams and Barcelona will need to join another league. That could be the French or the Spanish one."
Voters slashed the majority held by Mas's conservative alliance, Convergence and Union, but boosted support for left-wing pro-independence forces.
Opinion polls suggest around half of Catalans want independence including former Barca boss Pep Guardiola, who showed his support for a split from Spain by sending a message from New York as Catalans marched in favour of secession on their national day. Club president Sandro Rosell also took part in that same rally on September 11.
The Barca players, however, have been more diplomatic, fully aware that a pro-independence stance could harm their reputation within the Spanish national team.
Questioned recently by RAC1, Gerard Pique said: "I sincerely believe that, to begin with, it would make Catalunya and Spain weaker. Separation would weaken the two territories. After that, I don't know what would happen. We don't know."
Rosell claimed in September that the Catalan club would continue in Spain's top flight, even if the region were to win independence, but current rules mean Barca would be ineligible to participate in the Primera Liga should secession succeed, because only teams that form part of the Spanish Football Federation (RFEF) are allowed to compete in domestic competitions.
The Catalans' exclusion from the Primera Division would mean Real Madrid would be left without a rival of the same stature. Barca could come to an agreement to play in another competition such as France.