US banking giant JP Morgan has increased the amount of money set aside for potential litigation costs by $1.3bn (£813m), after revealing its currency trading operations were under investigation by the US Department of Justice (DoJ).The Financial Conduct Authority (FCA) in the UK and the Commodity Futures Trading Commission (CFTC) in the US both have ongoing probes into banks' currency trading policies and JP Morgan had previously made a provision of $4.6bn for settling various potential litigations, including forex trading.In its latest filing with the Securities and Exchange Commission (SEC) the bank indicated the sum had been lifted to $5.9bn.Five other banks, including HSBC, RBS, Barclays, Citigroup and UBS have also set aside funds for potential litigation costs related with settling the FCA's investigation into alleged rigging of foreign exchange markets.On Monday, HSBC announced it had set aside £236m, bringing the total potential costs set aside by the six banks to up to £4.73bn.