Britain's Serious Fraud Office announced on Monday that three more ex-employees of Barclays bank have been charged over the Libor rate-rigging affair. The scandal over Libor, an interest rate at the heart of the global economy, has damaged the reputation of London as a global financial centre and plagued big names in world banking. The Serious Fraud Office (SFO) said it had launched criminal proceedings against the three men "for conspiracy to defraud in connection with its investigation into the manipulation of Libor". The charged were named as Jay Vijay Merchant, Alex Julian Pabon and Ryan Michael Reich in a brief statement issued by the SFO, which added that its investigation would continue. The trio will appear at London's Westminster Magistrates' Court in a few weeks' time. A Barclays spokewoman declined to comment on the matter. The SFO has now brought a total of 12 charges in relation to Libor, including three other former Barclays employees. Libor, or the London Interbank Offered Rate, is a global benchmark that is calculated daily, using estimates from banks of their own interbank rates. It underpins the terms of $500 trillion of contracts from mortgages to the cost of corporate lending. The scandal erupted two years ago when Barclays was fined £290 million by British and US regulators for attempted manipulation of Libor and Euribor interbank rates between 2005 and 2009. Euribor is the eurozone equivalent of Libor. Royal Bank of Scotland, Swiss lender UBS, Rabobank and broker Icap have also received heavy fines over the scandal. The Libor system was found to be open to abuse, with some traders lying about borrowing costs to make their bank seem more secure or boost their trading positions. In the wake of the affair, the British Bankers' Association was forced to give up management of Libor, handing supervision over to stock exchange operator NYSE Euronext.