The City watchdog is investigating claims that power companies are manipulating wholesale gas prices.
The Financial Services Authority (FSA) and energy regulator Ofgem said they are both looking into the claims. Investigations have been launched after a whistleblower, named as Seth Freedman, claimed the gas market has been "regularly" manipulated by some of the big power companies, the Guardian reports.
Mr Freedman, who works as a price reporter for ICIS Heren, a company responsible for setting so-called benchmark prices, raised the alarm after identifying what he believed to be attempts to distort the prices reported by the company. It was also reported that Ofgem has been warned by ICIS Heren that it has seen evidence of suspect trading on September 28, the date that marks the end of the gas financial year.
An FSA spokesman said: "We can confirm that we have received information in relation to the physical gas market and will be analysing that material." Ofgem, the energy regulator, said it had also received information relating to trading in the gas market.
Energy Secretary Ed Davey said: "I am extremely concerned about these allegations and will be keeping in close touch with the regulators while they get to the bottom of this." It is understood the Treasury and the Department for Environment were alerted to the allegations - made by a whistleblower and reported by the Guardian newspaper - by Ofgem and the FSA on Monday. Mr Davey is expected to make a Commons statement on the matter on Tuesday afternoon.
An Ofgem spokesman said: "In preparing for full implementation of new EU legislation to tackle market abuse, we will consider carefully any evidence of market abuse that is brought to our attention as well as scope for action under all our other powers. Ofgem has already activated its established procedures to review the information we have received."
ICIS said in a statement that it has "detected some unusual trading activity on the British wholesale gas market on September 28 2012", which it reported to energy regulator Ofgem in October. "The cause of the trading pattern, which involved a series of deals done below the prevailing market trend, has not yet been established," an ICIS spokesman said. It is believed that on September 28 prices went down by about 0.4%.
Many of the UK's six energy companies spoke out about the allegations. EDF Energy said: "EDF Energy does not participate in loss-leading trading activity and considers it to be against existing market regulation." NPower said: "There is an explicit commitment in our code of conduct to comply with all laws and regulations." E.On said: "We are confident that all of our colleagues always act in the correct manner and as a company we fully abide by all appropriate regulations."
An SSE spokeswoman said: "We are entirely confident that our energy portfolio management team operate in a fair and legitimate way." A ScottishPower spokesman said: "ScottishPower has never engaged in trying to fix wholesale gas trading markets. Our trading division always acts with integrity and follows all rules in all of its engagements with the market."
Centrica, the UK's biggest energy supply company and parent company to British Gas, said in a statement that it wished to make its position clear in response to the claims: "Centrica has very robust governance and compliance policies, which regulate its market participation and behaviour. These policies are reviewed on a regular basis. Centrica's traders are prohibited from providing price information to price reporting agencies."