Energy suppliers in the UK have a margin of around £100 per customer due to the lack of cheap energy and a fall in wholesale costs, reports the BBC.
The research, from energy industry regulator Ofgem, suggests that prices in the wholesale market reached a peak at the end of 2008 and began a prolonged fall in the last few weeks.
Ofgem has published its first report in response to criticism that energy companies have been slow to reduce prices despite the rapidly declining cost of a barrel of oil.
So far, it has concluded that the strategy of purchasing energy on the wholesale market long before delivery is a major issue.
Robert Hammond, energy expert for watchdog Consumer Focus, told the BBC: "Consumers need firm reassurance that they are not being ripped-off by the energy companies, but that reassurance is sadly lacking in these findings."
The Energy Retail Association said the report demonstrated that consumer pricing was fair.
Energy companies have been criticised for failing to reduce prices during the recent sub-zero winter temperatures.
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