A referendum will be conducted on November 9, with potentially destructive results for the 22-time Spanish champions Barca and neighbours Espanyol.
Liga del Futbol Profesional (LFP) president Tebas said a 'yes' vote would make the two clubs' participation in the Spanish top flight illegal.
"Barcelona and Espanyol would not play in the Spanish League if Catalonia becomes independent for the following reason: the Sports Act has an additional provision that only one non-Spanish state can play in La Liga or official Spanish competitions, and that is Andorra," Tebas told Spanish radio station Onda Cero.
Tebas conceded if Catalonia did become independent, changes to the law secluding Barcelona and Espanyol from the league could be put on the agenda.
"For that to take place there would need to be a change in parliament and we'd need to see if the affected industry would agree or not," Tebas said.
On the issue of match-fixing, Tebas confirmed the LFP were investigating a fixture between Elche and Malaga - one of six matches under the microscope.
"I have not believed what has been said for some time now. I think it's been increasingly evident in recent times," Tebas said.
"Some dressing rooms are taking extreme weight from above. I don't know if Spanish football is prepared to see a player go to jail for a year, but there will definitely be penalties, just like the ones you see in other countries.
"We are investigating the Elche-Malaga game, but this one is a little different. We are looking at two [to] three players from the Malaga team but we're not sure about Elche yet.
"For the last four years, we've got six games that we're investigating.
"People want us to have a clean game. I haven't received a call from any manager who has taken issue with what we're planning to do."
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