Former La Liga referee Eduardo Iturralde Gonzalez believes the league is biased towards Real Madrid.
The official, who took charge of 291 games across 17 seasons, claims 90 per cent of referees will side with Los Blancos while the other 10 will back Barcelona.
Between them the two clubs have won 14 of the last 15 titles and dominated domestically.
And Gonzales told the El Larguero podcast that the bulk of Spain follows one of the country's giants: "Around 90 per cent go with Real and 10 per cent with Barcelona. Whether Barca fans like it or not, 70 per cent of the Spanish population, excluding Catalonia, are Real Madrid supporters.
"There are more Barca fans these days because the younger generation has seen the trophies they won under Pep Guardiola.
"But before the Lionel Messi era, how many people supported Madrid in Spain? About 70 per cent?"
Gonzales has previously made his opinion known on the matter.
Having retired in 2012 he spoke to Marca two years later and reiterated his belief that the bulk of the country and rooting for Madrid.
He said: "Personally, I don't care about one or the other. I'm Athletic Bilbao. Everyone knows that I am Athletic, but I would go against them to try and be fair.
"I'm lucky to have been born in Bilbao. Everyone is Athletic there.
"But in the rest of Spain, the majority are Real Madrid of Barcelona fans, because they're the teams that win.
"And that's how it is. And the majority are Real Madrid."
Gonzales' views have provoked a reaction but he claims "that does not mean that when they whistle for Madrid, they are not professionals".
Madrid and Barcelona are battling it out for the title once again this term with La Liga due to resume in June.
