Exchange rate fears raised in 2009
24 December 2013 Last updated at 00:08 GMT
The BBC has learned that banks were aware of problems in the foreign currency markets four years before the Financial Conduct Authority began its investigation into the fixing of exchange rates.
Analysts had noticed sharp movements in exchange rates at key times of day and warned their clients it could have a 'debilitating effect' on their investments.
Hugh Pym reports.