Previously BP had said that just the CFTC was carrying out an investigation, with probes going back only as far as 2002.
The energy company said that it was cooperating with "various formal and informal requests for information".
BP has previously been hit with a $100,000 fine from the CFTC, after one of its traders was accused of being involved in "wash trades" in 2000. It has previously been the subject of three probes in the US since June 2006 for allegedly manipulating propane, crude oil and petrol prices between 2002 and 2004.
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