La Liga president Javier Tebas accused Nasser Al-Khelaifi of lying and arrogance on Wednesday after Paris-Saint Germain's president defended his club's lavish spending to keep Kylian Mbappe.
La Liga have filed complaints to UEFA about PSG and Manchester City "continuously breaching the current regulations of financial fair play", the Spanish league confirmed last week.
Quoting Al-Khelaifi's comments on Twitter, Tebas wrote on Wednesday: "Al-Khelaifi is another level. He takes us all for fools (not even he believes his lies) and shows up in @marca preaching with pride and arrogance about the 'nouveau riche'.
"The rules do not exist for @PSG_inside. We will continue to fight for a football that is sustainable and without cheating."
Tebas has long-rallied against the financial wealth of state-backed clubs like PSG and City, who he insists are constantly breaking UEFA's financial fair play rules and disturbing the economic balance of the game.
As well as its complaint filed to UEFA against the two clubs, La Liga has hired legal firms in France and Switzerland "with the aim of undertaking administrative and judicial actions before the relevant French bodies and the European Union as soon as possible," La Liga said last week.
The league is also considering taking action against Al-Khelaifi regarding a "conflict of interest". Al-Khelaifi is PSG president, in charge of Qatar-owned BeIN Sports, leads the European Club Association and also sits on UEFA's executive committee.
PSG suffered a 224.3-million-euro ($240m) loss in 2020/21, an increase of 80 percent on the previous year, the annual report from French football's financial authority (DNCG) said earlier this month.
Real Madrid president Florentino Perez said last week Mbappe was left "confused" after being put under intense "political and economic pressure".
Al-Khelaifi said PSG rejected an 180-million-euro bid from Real Madrid last summer because he knew Mbappe wanted to stay.
"I rejected 180 million last summer from Real Madrid because I knew that Kylian wanted to stay at PSG. I know him very well, I know what he and his family want, and they don't move for money," he said.
"He has chosen to play here for his city, his club and his country, and for the sporting project. He only thinks about playing and winning."