La Liga president Javier Tebas has accused big-spending duo Paris Saint-Germain and Manchester City of "financial doping" in recent years.
City have splashed out over a billion pounds on players since being purchased by the Abu Dhabi United Group nearly a decade ago, including £215m during the most recent window.
PSG, also under the ownership of wealthy Middle Eastern backers, have themselves taken transfer spending to a new level this summer as they paid £198m for Brazilian forward Neymar and agreed to hand over £166m to sign Kylian Mbappe permanently next year.
Two days on from calling on UEFA to investigate Man City's spending, Tebas has once again taken aim at the Citizens and also accused PSG of financial wrongdoing.
"Recently, Manchester City and Paris Saint-German, before that Chelsea, they have money that has not been created [by them] and have been able to get an advantage through this," he told reporters. "Manchester City with all this oil [money] will take all these players and we need to protect ourselves. These past few years Manchester City have paid out nearly a thousand million on players, PSG £950m.
"We have seen the accounts of these clubs for the past five years, seeing income from gate tickets, TV rights and commercial income. This is publicly available data. We have the comparison with Real Madrid, Barcelona and Manchester United. We know these clubs fight to become the best brand in world.
"We carried out this study of the accounts - income streams, sponsorship, etc. PSG has a lot more from sponsorship than Manchester United. That's impossible. That's financial doping. It is not like I don't like PSG. If [Neymar] had gone to Manchester United maybe I would not have gone to the courts because this is not financial doping and maybe they have the money to buy this player."
PSG chairman Nasser Al-Khelaifi used the unveiling of Mbappe on Wednesday afternoon to defend his side's huge outlay on new arrivals.