France's top lenders are suing the European Central Bank to get an exemption from holding capital against deposits parked with a state-owned fund, the most high-profile challenge to supervision from Frankfurt to date.
As well as providing euro zone banks with funding, the ECB has been their main regulator for the past two years, tasked with ending cozy relationships between the industry and national authorities that contributed to the financial crisis.
The Frankfurt-based institution has been sued repeatedly over its bond-buying programs and by smaller banks seeking to escape its supervision.
But this is the first case brought by major banks in the euro zone and is a rare confrontation between France's financial elite and the ECB's supervisory board, led by the former head of France's own banking regulator, Daniele Nouy.
The lawsuits have been brought by BNP Paribas, Societe Generale, Credit Agricole, Credit Mutuel, Groupe BPCE and La Banque Postale over the past few weeks, filings with the European Court of Justice show.
Sources with direct knowledge of the cases told Reuters the banks are protesting the ECB's demand that they set aside capital against special deposits they have with state investment institution Caisse des Dépôts et Consignations (CDC).