Energy firms have been accused of failing to pass on £1 billion of cost savings to customers.
Joe Malinowski of price comparison website TheEnergy Shop.com claimed households were paying an estimated £200 a year extra for fuel because firms were slow to cut prices when costs fall.
Last week, energy supplier npower increased the price of gas by 17.2 per cent and electricity by 12.7 per cent, citing rises in wholesale energy costs.
Other suppliers are expected to follow suit with similar price increases imminently.
Mr Malinowski said: "This industry has never passed on the full benefits of the falls in 2006, but has been very quick to pass on the latest increases."
Energyhelpline.com, a price comparison website, said prices should have fallen by an additional ten per cent last year prior to tariff increases.
And comparison firm uSwitch said suppliers withheld £177 in price cuts from every household in Britain last year.
People could increase their savings on energy bills by looking for the Energy Saving Recommended logo on their new energy consuming products.
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