Britain's Barclays has suspended several traders amid multiple investigations into possible manipulation of benchmark foreign exchange rates, a banking industry source said on Friday.

A string of banks, including Standard Chartered, JP Morgan and Citigroup, have put dealers on leave as regulators in the United States, Europe and Asia investigate whether there has been manipulation in the $5.3 trillion-a-day foreign exchange market.

Barclays said in its results on Wednesday it was reviewing its currency trading operations and cooperating with authorities in their probes.

Barclays declined further comment then or on Friday.

Citigroup and JP Morgan disclosed on Friday that various authorities were questioning them about their currency trading operations in their quarterly filings with the U.S. Securities and Exchange Commission.

Royal Bank of Scotland also said it was co-operating with various governments and regulators in the investigation and reviewing communications and procedures used by its traders.

RBS declined to comment on Friday on a report in the Financial Times that said it had suspended two traders in its foreign exchange division.

In echoes of the global probe into the manipulation of benchmark interest rates, authorities are investigating whether traders at investment banks colluded with counterparts at other banks to try and rig benchmark FX rates, tipping each other off about their positions to try and influence the rate set.

Benchmark FX rates, often referred to as fixes, are a cornerstone of global financial markets, used to price trillions of dollars worth of investments and deals and relied upon by companies, investors and central banks.