By Matt Scuffham LONDON (Reuters) - Britain's anti-fraud agency will get any extra funds it needs to pursue a criminal investigation into alleged rigging of the $5.3 trillion-a-day currency market, a finance ministry source said on Friday.
The Serious Fraud Office (SFO) had last month asked for an extra 26.5 million pounds ($41.5 million) to help fund complex inquiries into issues such as financial benchmark manipulation, but the source did not say how much would be given.
The SFO investigates and prosecutes high-profile cases with a relatively meagre annual budget, set this year at 35 million pounds ($55 million), which is under pressure given the list of issues it is probing.
These also include an inquiry into Barclays Plc's 8 billion pound money-raising in 2008 and an investigation into accounting practices at retailer Tesco Plc, as well as looking into the manipulation of benchmark interest rates such as Libor.
The source said finance minister George Osborne had written to the SFO, which can request "blockbuster funding" if the cost of cases exceeds a percentage of its budget, to say it will be given the financial support it needs for the forex probe.
The SFO opened a criminal investigation into allegations of fraudulent conduct in the forex market in July and said individuals could be charged next year.
"Given the importance of this work, the Treasury will provide the required funding for this investigation. We must continue to pursue criminal wrongdoing at the highest level," Osborne wrote in his letter to the agency, the source said.
The SFO's foreign exchange probe is in addition to a regulatory clampdown which resulted in six major banks being fined a total of $4.3 billion on Wednesday.
The fines were for failing to stop traders from trying to manipulate the foreign exchange market, following a year-long global investigation.
The levies brought total global penalties for manipulation of financial benchmarks to more than $10 billion over two years.
Royal Bank of Scotland, HSBC, JP Morgan, Citigroup, Bank of America Corp and UBS were hit with penalties. Barclays is still in talks with authorities over a settlement.
Britain is keen to be at the forefront of global inquiries into the forex market, partly because about 40 percent of it is based in London.
(1 US dollar = 0.6376 British pound)
(Editing by Alex Smith and David Holmes)