Law firm Maurice Blackburn has launched a class action against five international banks, claiming they colluded to rig foreign exchange. The firm filed the class action in the Federal Court yesterday, suing UBS, Barclays, Citibank, Royal Bank of Scotland and JP Morgan.According to the claim, traders from these banks used chat rooms with names such as "The Cartel", "The Bandit's Club" and "The Mafia" to co-ordinate the manipulation of FX benchmark rates, control the pricing of spreads and trigger stop loss orders and limit orders.The alleged effect of this activity was to artificially increase the cost of buying certain currencies and decreasing the price received when selling. There were 29 affected currencies. The action is on behalf of foreign exchange customers that bought or sold currency between January 2008 and October 2013. The case will be represented by lead plaintiff J Wisbey and Associates, an importer of dental and medical equipment.Maurice Blackburn claims Australian institutional investors and businesses, particularly importers, exporters and those with operations overseas, were adversely affected by the distortion of the FX market.The claim is linked to alleged cartel conduct in the FX market that has been the subject of regulatory and legal action in the United States and Canada involving the same banks. "Settlements in the US and Canadian class actions have so far resulted in the payment of over US$2.3 billion and C$107 million," Maurice Blackburn said in a media release.Citi, RBS, JP Morgan and Barclays were among five banks that agreed to pay European Union fines totalling €1.7 billion earlier this month for colluding on foreign exchange strategies.The firm opened a registration portal yesterday, so it is not clear at this stage how big the class will be. Being eligible, the publisher of Banking Day has registered for this class action.