The Financial Services Authority and energy regulator Ofgem are to investigate allegations that UK energy companies rigged gas prices.
The Department of Energy and Climate Change announced the probe following allegations in the Guardian that UK gas prices had been manipulated.
Energy secretary Ed Davey said he was “extremely concerned about these allegations”. He added he will be “keeping in close touch with the regulators while they get to the bottom of this.”
The FSA and Ofgem will be examining evidence passed onto them by the whistleblower to examine whether it could be used in civil or criminal proceedings.
Britain’s biggest gas supplier Centrica said it has a “very robust governance and compliance policies, which regulate its market participation and behaviour”.