Manchester City and Paris Saint-Germain have been denounced to UEFA by LaLiga for allegedly breaking the Financial Fair Play (FFP) rules.
Javier Tebas, the president of LaLiga, has also chastised the Premier League for saying that spending rules "do not exist."
Tebas is enraged after Real Madrid failed to sign Kylian Mbappe, who has agreed to a three-year contract worth £200 million.
Erling Haaland, who turned down a move to Spain this summer, has joined City in a £51 million deal.
"La Liga understands that these clubs' irregular financing is carried out, either via direct money injections or through sponsorship and other arrangements that do not conform to market conditions or make economic sense," La Liga said in a statement.
"La Liga believes that these activities impair the ecosystem and long-term viability of football, affect all European clubs and leagues, and serve simply to artificially inflate the market with money earned outside of football."
PSG and Manchester City have both been contacted for comment and have previously categorically denied any wrongdoing.