Only one in 10 households will be eligible for assistance under Government plans to force energy companies to move customers onto their lowest tariffs, Labour claimed today.
Legislation going through Parliament would give Energy Secretary Ed Davey the power to require companies to switch households onto cheaper tariffs if they are currently on "closed tariffs", which are no longer being offered to new customers.
But figures obtained from the "Big Six" gas and electricity suppliers by shadow energy secretary Caroline Flint suggest that closed tariffs account for only about 2,530,000 of the 27 million households receiving energy nationwide.
British Gas told Labour that it had no customers at all on closed or dead tariffs, while npower had just 28,000. Scottish Power had 100,000 customer accounts on the tariffs, EDF 113,000, E.On 489,000 and SSE 1.8 million.
A Labour source said: "Based on Department for Energy and Climate Change (Decc) estimates, there are over 27 million households with gas or electricity accounts, which suggests that over 90% - according to the energy companies' own figures - will be unaffected by David Cameron's promise to put everyone on the lowest tariff."
A Decc spokesman said: "These figures are misleading. The reforms are yet to kick in, and the numbers will change dramatically when they do.
"Before the end of the year, energy suppliers will be forced to offer no more than four core tariffs per fuel.
"As these changes take effect, more people will be on tariffs closed to new customers, and suppliers will need to move these customers on to the best deal for their preferences.
"Suppliers will also be required to tell all their own customers if there is a cheaper tariff for them, and people will benefit from clearer information to help them compare and switch suppliers."