Britain's Serious Fraud Office (SFO) has made the first arrests as part of a global investigation into the manipulation of interbank lending rates.
The SFO said on Tuesday three British men, aged 33, 41 and 47, had been taken to a London police station for interviews. They had all been living in Britain.
Sources had said that regulators and prosecutors in the U.S. and Europe were closing in on individual traders they suspected of colluding to rig key benchmark lending rates such as Libor (London interbank offered rate) and its euro cousin Euribor.
Libor, which underpins around $550 trillion of loans and financial contracts, hit the headlines in June when Barclays was fined a record $450 million for allowing traders to rig it and Euribor and for low-balling rates during the 2007/08 credit crunch.
Other banks remain under investigation in Europe, the United States, Canada and Japan, while UK and U.S. regulators stand accused of either condoning or failing to stop manipulation as the financial crisis brought banks to their knees four years ago.