Cameron accused over energy tariffs
Three-quarters of households are paying up to £250 a year more than their energy company's cheapest tariff two years after David Cameron promised to force suppliers to put all customers on the best deal, Labour has said.
Shadow energy secretary Caroline Flint said Department for Energy and Climate Change (DECC) figures showed that 75% of households were on their supplier's standard variable tariff.
The standard variable tariff was on average more than £180 a year more expensive than the cheapest tariff, with some customers paying nearly £250 a year more, Ms Flint said.
She said Mr Cameron had promised 17 times in the House of Commons to make energy suppliers automatically put all customers on their supplier's lowest tariff.
She said: "More than two years after David Cameron promised to make energy companies put all customers on the lowest tariff, millions of households are still being routinely overcharged by hundreds of pounds every single year.
"That's why the next Labour government will freeze energy prices until 2017, so that bills can fall but not rise, give the regulator the power to force energy suppliers to cut their prices and end overcharging once and for all."
Last month the Competition and Markets Authority (CMA) released early findings of an inquiry into the sector that the Big Six were overcharging millions of loyal customers by up to £234 a year.
Its findings showed 95% of the UK's 19 million dual fuel customers - those who take gas and electricity from the same company - could have saved between £158 and £234 by switching tariff or supplier.
The CMA found the Big Six had consistently charged higher prices for standard variable tariffs than for other deals such as fixed tariffs.
Energy UK chief executive Lawrence Slade said: "Standard variable tariffs are just that, the standard price a company is offering energy to customers.
"Part of the cost of energy is an assurance that the gas and electricity has been bought months in advance, making sure energy will be available to customers when it is needed.
"New fixed-price deals are able to take advantage of short-term changes in costs and usually offer lower prices than the standard deals, often for a year or two.
"However, the important thing for customers to remember is there are a wide range of deals available in the market.
"If a customer thinks they might be able to save some money by switching tariff or company, they should log on to a comparison site or call their supplier."
Ofgem chief executive Dermot Nolan said: "While recent price cuts are a step in the right direction, many customers could be better off to the tune of up to £250 by moving from a variable rate to a fixed rate deal.
"If you're not sure where to start, then I'd strongly recommend the Be An Energy Shopper website for an independent and impartial guide."
A Decc spokeswoman said: " Our reforms to drive down household bills are working and the best energy tariffs are cheaper than they were a year ago. But people want to see more savings - now - and the power is in their hands to do something about it. By shopping around for a better deal and switching energy suppliers households can save around £200 and some even more.
"Consumers deserve a fair deal - and this is exactly why we're backing the CMA's investigation."