Agents at the FBI’s Washington HQ are conducting an inquiry into the group accused last week by regulators of conspiring to rig international interest rates. The FBI could attempt to extradite any Britons involved in the affair to the United States if it finds there is a case to answer. It has also been claimed that the US justice department has a 28-page statement of facts disclosing how a network of traders working on both sides of the Atlantic conspired to influence the interbank lending rate. The document reportedly states that the collusion took place from at least August 2005 through to at least May 2008. It says certain Barclays traders communicated with former colleagues who had joined other financial institutions.