There are too many cases where people have found themselves unknowingly transferred to another supplier, or been hassled on the doorstep by unscrupulous salesmen.

Ann Robinson, Energywatch

But the move nonetheless represents a potentially controversial strategic shift for the regulator, which has so far been in tough in limiting utility price rises.

Consumers are concerned that recent sharp falls in the price of oil - which is closely linked to wholesale gas and power prices - will not be passed on in utility bills.

Hassled

Consumer group Energywatch said it challenged Ofgem's "assumption" that the energy market was working well.

Ann Robinson, who chairs the group, said: "There are too many cases where people have found themselves unknowingly transferred to another supplier, or they have been hassled on the doorstep by unscrupulous salesmen.

"Another big issue is that some of the most vulnerable people cannot get access to cheaper fuels because they are in debt to their current supplier or don't have access to a bank account.

"This raises serious concerns about how this market in working for a significant number of people, especially the fuel poor."

Savvy shoppers

Ofgem's decision was based on research indicating that consumers are becoming increasingly savvy about shopping around.

According to the regulator, some 100,000 power users and 67,000 gas customers are currently switching suppliers every week, with low-income customers migrating at the fastest rate.

"The focus of Ofgem's work going forward will increasingly be on monitoring competition and using competition law to tackle market abuse," Ofgem chief executive Callum McCarthy said.

"I would urge all customers to shop around for the best deals as there will be continuing pressure on prices."

Measures aimed at helping vulnerable customers, and work on making it easier for customers to choose and change suppliers, will also be prioritised, Mr McCarthy said.