Javier Tebas, president of Spain's La Liga, believes that Qatari-owned French side Paris Saint-Germain are "laughing" at the financial fair play (FPP) system.
The 55-year-old issued a warning that if UEFA's response to La Liga's concerns, regarding the lavish spending of both PSG and Abu Dhabi-owned Manchester City, was not satisfactory, then he would take the case to Brussels and the European Union.
PSG 'laughing at' FPP system: La Liga chief
What are FFP rules?
According to UEFA, the FFP, introduced in 2010, is "about improving the overall financial health of European club football".
It was the brainchild of Michel Platini, the former president, and was intended to force clubs to spend within their means and thereby prevent them from running into huge debts and the risk of bankruptcy.
Essentially, "clubs have to prove they have paid their bills".
PSG, City spent millions in the summer transfer window
Then, they loaned AS Monaco's highly-rated youngster Kylian Mbappe, with an option to buy him for 180 million euros next season.
City, as well, spent almost 242 million euros in the window, as they signed Danillo, Bernardo Silva, Ederson and Kyle Walker.
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UEFA investigating PSG's transfers
UEFA has launched an investigation, promising to see whether or not PSG has broken any FPP rules.
Tebas said, "PSG are laughing at the system. All PSG have to do is turn the gas tap. This is what they have been doing for the past four years. We have to get a system that is fair to the victims."