The Labour front bencher claimed that the major electricity suppliers in the UK have been buying wholesale energy at above the market price.
The figures, which compared the purchase price of wholesale electricity for British Gas, EDF Energy, Eon, Npower, Scottish Power, and SSE, with First Utility, and found the difference of more than £3.8 billion since 2009. This equates to an average of £150 per customer.
Flint said: “These figures reveal the full extent of the way consumers have been overcharged for their electricity.
“Energy companies always blame wholesale costs when they put up bills, but it now looks like they’ve deliberately inflated prices to boost profits from their power stations.
“The regulator Ofgem has serious questions to answer about why it has failed to monitor the way in which companies have bought electricity from themselves and why it has allowed these companies to overcharge their customers.”
A spokesperson for Ofgem said: “Ofgem has not seen the details of the Labour Party’s analysis that forms the basis of its allegations that consumers have been overcharged for their energy.
“We would clearly consider more detailed information as part of our state of the market report in March. Ofgem regularly looks at the relationship between wholesale and retail prices and our own analysis of the evidence does not support this allegation.
“Where we have found evidence that firms have not played by the rules we have acted.”
The spokesperson added: “We are already addressing concerns about transparency through our reform programme.
“This includes increasing transparency in the wholesale electricity market by pushing through reforms to increase trading in the market and to ensure the big six energy suppliers have to post out two years in advance the prices they will sell electricity in the forward markets.”
In a statement, Energy UK said the suppliers pay “the most competitive price they can” for wholesale gas and electricity, and added that the wholesale prices published by the suppliers “include a number of costs so are not purely market prices”.
A spokesperson from the Department of Energy and Climate Change added: “The Government is already implementing the biggest reform of Britain’s wholesale and retail energy markets in a generation – improving liquidity and making other changes to drive competition and make things simpler, clearer and fairer for consumers.”