Giant investment banks Citigroup Inc. and JPMorgan Chase & Co. have put their top level currency dealers from London, according to a Bloomberg report. The move of the investment banks took place right aftert investigation by regulators, according to three anonymous sources.

Regulators had been probing the investment bank's traders regarding foreign-exchange rate manipulation. The sources said the traders had used an instant-message group that might have been instrumental to the rate manipulation scheme. 

According to one of the anonymous sources, Citigroup's Rohan Ramchandani, who was head of its European spot trading, was placed on leave. At JPMorgan, its chief London currency dealer Richard Usher went on leave two weeks ahead of the investigation. According to the sources, both Ramchandani and Usher took leave under a mutual agreement. The two have not been suspended.

Other investment banks were also identified during the regulators' probe. The probe included banks Standard Chartered Plc., Barclays Plc., Royal bank of Scotland Group Plc., and UBS AG.