A probe has been launched into alleged gas price manipulation amongst UK energy firms - a claim that the companies have been quick to refute.
Both the Financial Services Authority (FSA)Â and Ofgem are now looking into 'unusual trading activity' which occurred in late September - specifically on 28 September, which marks the end of the gas financial year.
UK energy secretary Ed Davey said, in a statement, that he was â€œextremely concernedâ€ following the recent allegations.
He said: â€œ[We] will be keeping in close touch with the regulators while they get to the bottom of this.â€
The shadow energy secretary, Caroline Flint, said that if the reports were true it would suggest 'shocking behaviour' in the energy market.
In an interview with ITV1's Daybreak she said: "Our energy bills have gone up by over Â£200 in recent years and in the last few weeks prices have gone up again so these latest allegations couldn't have come at a worse time for people trying to heat their homes.
"We need a situation when all the energy is put in a pool and the people who trade in it do it in an open and transparent way."
ScottishPower, SSE, nPower, EDF Energy and British Gas owner, Centrica - all of which are partaking in the Warm Home Discount Scheme - have released separate statements denying their involvement in any kind of misconduct to do with pricing.
ScottishPower's statement read: "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."
While SSE stated: "We are entirely confident that our energy portfolio management team operate in a fair and legitimate way."
A statement from nPower read: "There is an explicit commitment in our code of conduct to comply with all laws and regulations."
EDF Energy said: "EDF Energy does not participate in loss-leading trading activity and considers it to be against existing market regulation.
"We will make information likely to impact market price formulation publicly available on our website in compliance with the European Union's Regulation on Energy Market Integrity and Transparency (REMIT)," its statement concluded.
Centrica, meanwhile, stated: "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."
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