Energy companies have been severely criticised for not cutting their gas prices, despite a sharp drop in the cost of wholesale gas, with at least 23 million households still waiting for the savings to be passed on to them.

Wholesale gas prices have dropped on average by 50% since June 2006, but many fuel bills, costing £1,000 per household in many instances, have not decreased at all.

Only two of the ‘big six’ energy providers – EDF Energy and Scottish Power – have cut their prices to date. Two others – Npower and Powergen – have pledged to cut bills but have delayed the move until 30th April. The remaining two companies – EDF Energy and Scottish Power – have not cut prices at all.

A spokesperson for watchdog Energywatch said: “They are always quick to increase prices when their wholesale costs go up. But they are always slow to cut them when the wholesale prices come down.”

He concluded: “Even the companies that have cut their prices should have cut them by more than they have done.”

Energy regulator Ofgem has promised to investigate any firm that fails to cut bills if the wholesale cost has declined. Chief executive, Alistair Buchanan said: “If companies are tempted to keep some of the jam on their fingers, they might in effect be triggering us into having a look at what is going on.”