Energy firms will be forced to give customers the cheapest available tariff under new legislation, David Cameron has announced.
Amid mounting concern about rocketing fuel bills, the Prime Minister signalled plans to introduce new laws to tackle the often-confusing array of tariffs.
"I can announce that we will be legislating so that energy companies have to give the lowest tariff to their customers," he told MPs during Prime Minister's Questions.
His intervention follows a string of above-inflation price hikes by major energy companies in recent days.
Ministers have previously encouraged consumers to shop around and make sure they are on the best available deals. They have also announced moves to require energy companies to inform their customers if they could be on cheaper tariffs.
But the forthcoming Energy Bill will go further by introducing a requirement for companies to give people the best tariff for their circumstances.
The move is intended to tackle concerns that many householders, at a time of rising fuel costs, are already paying more than they need to because of the bewildering number of deals available.
Mr Cameron's announcement came as he, Deputy Prime Minister Nick Clegg and Chancellor George Osborne were expected to hold a meeting on the Government's energy policy today.