A specialist American law firm launched a class-action lawsuit against six banks at the U.K. Competition Appeal Tribunal to seek compensation for customers affected by cartels allegedly formed to manipulate foreign exchange prices, the Financial Times reported Dec. 11.

Banks involved in the action are Barclays PLC, Royal Bank of Scotland Group PLCThe Royal Bank Of Scotland, Citigroup Inc., UBS Group AG, JPMorgan Chase & Co. and Mitsubishi UFJ Financial Group Inc.

The lawsuit was filed by U.S.-based Hausfeld LLP under the leadership of Phil Evans, a former Competition and Markets Authority inquiry chair. Evans said the purpose of the collective action is to compensate those affected by the cartels, as a €1 billion fine previously imposed on the banks by the European Commission did not go to the victims.

The commission had said the banks it fined took part in two cartels in the spot exchange market for 11 currencies.

The litigation alleges that traders at 15 banks colluded to manipulate prices in currency markets between 2007 and 2013, according to the report.