The Serious Fraud Office (SFO) has launched a criminal investigation into allegations of price rigging in the £3tn-a-day foreign exchange market.
The probe will look into allegations of “fraudulent conduct”, the director of the SFO said in a statement.
Around 15 international agencies are investigating allegations of collusion and price manipulation.
It is alleged that traders used online chatrooms to plan the fixing of benchmark prices.
The Financial Conduct Authority (FCA) said in October it had joined other regulators around the world in scrutinising firms over the potential manipulation of the foreign exchange market.
Several investment banks, including Barclays and HSBC have already suspended currency traders due to the investigation by the FCA.
And in March this year the Bank of England suspended one member of staff over the probe.
At the time the head of the Financial Conduct Authority, Martin Wheatley, said that currency manipulation was “every bit as bad” as the Libor scandal, where banks including Barclays, Royal Bank of Scotland and UBS paid fines totalling $6bn relating to Libor fixing.
For the criminal probe the SFO will work in co-operation with the FCA and the US Department of Justice, which announced its own criminal investigation last October.
Earlier this year US prosecutors flew to London to question individuals over allegations of market manipulation.