David Cameron has sparked confusion among his senior ministerial team after announcing apparently without their knowledge new legislation that would force energy companies to put their customers on the cheapest tariff available.

In response to a question about rising energy bills, the Prime Minister told the commons: “I can announce that we will be legislating so that energy companies have to give the lowest tariff to their customers”

His choice of words appeared to indicate that the Government would be forcing all energy companies to offer the cheapest tariff to everyone in the UK. However, when quizzed on the PM’s announcement, neither Energy Secretary Ed Davey nor his minister John Hayes appeared to know what Cameron was talking about.

In an attempt to clear up some of the confusion surrounding the issue, Davey told ITN News: “ The Deputy Prime Minister, Nick Clegg, announced in April an agreement that I negotiated with the ‘big six’ [energy companies] that they will have to tell their customers every year what’s the best available tariff.” However, the Energy Secretary stopped short of saying that the Government would be legislating to force energy companies to put customers on the lowest available tariff.

Late last night, Cameron muddied the waters further by apparently sticking to his initial statement, telling journalists in Brussels: “We are going to use the forthcoming legislation, the energy bill coming up this year, so we make sure, we ensure, that customers get the lowest tariffs. That's what we're going to do.”

Shadow Energy Secretary, Caroline Flint, hit out at the proposed plans, stating: “Energy bills have gone up by more than £200 since this Tory-led Government came to power. The Government’s last-minute decision to force energy companies to put customers on the cheapest tariff, after most energy companies have already announced price hikes, is an admission that their ‘do nothing’ energy policy over the last two years has failed.

“The cheapest deal in an uncompetitive market will still not be a good deal for the public unless we completely overhaul our energy market to break the dominance of the big six energy companies and create a tough new watchdog with powers to force energy companies to pass on price cuts. Until we see real action from the Government, the Prime Minister’s warm words in the House of Commons will be cold comfort to millions of families worried about how they will pay their energy bills this winter.”

However, Richard Lloyd, Executive Director of consumer body Which? has urged the Prime Minister to stick to his initial pledge, commenting: “The Prime Minister must stick to the promise he made in Parliament to legislate so energy companies have to give the lowest tariff to their customers. Just giving people information on the lowest tariff is not enough when trust is at an all time low in the industry and switching levels are falling. Which? has been pressing the Government for years to make sure people get a better deal so we must now see these words turned into action.”