Trials not expected to start until early 2015 LONDON, Dec. 17 (UPI) -- Three men in London pleaded not guilty Tuesday to charges revolving around manipulation of the benchmark London interbank offered interest rates. The Wall Street Journal reported that former UBS and Citigroup Inc. trader Tom Hayes and former R.P. Martin Holdings Ltd. brokers Terry Farr and James Gilmour, entered not guilty pleas in a hearing in a packed courthouse. The benchmark rate, known as the Libor, is used to set interest rates for trillions of dollars of commercial and personal loans. It is also used in many other market transactions. Barclays, UBS, the Royal Bank of Scotland Group have together paid $2.5 billion in fines to settle charges of Libor manipulation in recent months. Several other larges banks have been caught up in the scandal. The charges in London were filed by the Serious Fraud Office, which now has a more difficult case than previously thought, as one of the men charged, Hayes, was previously reported to be willing to plead guilty and cooperate with authorities, the Journal said. Hayes, however, hired a new legal team over the summer and is set to defend himself against the charges. An attorney for the regulator Mukul Chawla said the case against Hayes and others could now turn on the cooperation of other individuals. "There are a number of individuals whose activities in regard to Mr. Hayes are being considered," Chawla said in the hearing room presided over by Judge Jeremy Cooke. Chawla also said the he would present further evidence at a hearing in April, including expert testimony that will have the job of clarifying how the Libor affects various bank transactions, so the jury and other lawyers could understand it. At this, Cooke said clarifying the financial products could also be helpful for some of the finance professionals in the room. So some of those who trade in them can understand them, The trials on the Libor case are not expected to begin until sometime in early 2015, the Journal said.