Three men arrested in connection with an investigation into the manipulation of Libor, the interbank lending rate, were an ex-trader who worked for UBS and two interdealer brokers, a report said.
The arrests were made on Tuesday in London, the Serious Fraud Office (SFO) said.
Tom Hayes (33), a former trader who specialised in products pegged to yen-dominated Libor, was taken to a police station following a search of his home. Terry Farr and Jim Gilmour, two employees of RP Martin, a London-based interdealer broker, and believed to be known to Hayes, were also questioned.
At the height of the banking scandal this summer, the SFO revealed it had been working closely with the Financial Services Authority (FSA).
The arrests follow speculation that Swiss banking giant UBS has started settlement talks with regulators over alleged Libor rigging.