Three men arrested in UK Libor inquiry Three British men, including a former UBS trader and two employees of interdealer broker RP Martin, have become targets of the first arrests in a sprawling worldwide probe into manipulation of the London interbank offered rate. The UK's Serious Fraud Office said on Tuesday it had arrested three men aged 33, 41 and 47 and the suspects were "all British nationals currently living in the United Kingdom." Tom Hayes, who has previously worked at both UBS and Citigroup, is one of those arrested, two people familiar with the investigation told the Financial Times. Mr Hayes" lawyer was unavailable to comment. UBS and Citi both declined to comment. The RP Martin employees are Terry Farr and Jim Gilmour, according to several people with knowledge of the situation. They have been on leave from the firm for close to a year. RP Martin declined to comment except to say that the interdealer broker itself is not under investigation. Lawyers for the two men could not be immediately reached. The SFO made the arrests with the assistance of the City of London police after searching homes in Essex and Surrey. The suspects were being questioned in a London police station. The arrests mark a ratcheting up of the Libor probe, where about 10 authorities across the globe are scrutinising some 20 banks and other financial institutions, including interdealer brokers. UBS's fine may top that meted out to Barclays, people familiar with the situation have told the FT. Mr Hayes has previously worked for both banks. In addition to Citi, his employment history also includes the Royal Bank of Canada. Mr Hayes worked as a derivatives trader on the macro desk of UBS from late summer 2006 until September 2009. The 33-year-old trader then went on to work for Citi at its yen rates trading desk, but left there after less than 10 months in September 2010. One person familiar with his time at Citi said he did not get his trading book before April 2010 and left by the summer of that year. The SFO, under budgetary and reputational pressure, had to secure an extra £3.5m from the UK Treasury to begin its criminal probe. The former director had previously decided to leave the investigation in the hands of the FSA and other agencies because of concerns over duplication and limited resources. What will be more interesting is how far up the chain of command the evidence leads ... The agency's focus on British nationals signals a narrow remit in an investigation where many agencies are vying for territory. The global nature of modern finance means suspects of various nationalities are spread all over the world. Law enforcement officials have previously expressed concern to the FT that UK suspects who were in the country at the time of the alleged wrongdoing should be prosecuted by its authorities and that a "NatWest Three" situation should not be repeated - a reference to three British bankers who were extradited to the US in 2006 to face Enron-related charges brought by the Department of Justice. With additional reporting by Sally Gainsbury and Nizar Manek in London