The UK's 'big six' energy companies have been told to lower their prices if they are to "regain the trust" of the British public.
The UK's leading energy providers, British Gas, SSE, Scottish Power, Npower, EDF and E.On, have come under increasing pressure to lower their bills after the price of wholesale gas fell by 20% since December.
The companies have made reductions since then but on a much smaller scale. Npower, British Gas, E.On, Scottish Power and SSE reduced bills by between 3.5% and 5%. EDF Energy prices are down by 1.3%.
With the companies failing to match the market discounts, Energy Secretary Amber Rudd has written to them, urging the companies to pass the savings to the consumers.
In a letter obtained by the BBC, Rudd wrote: "In light of the greater regulatory stability we are providing and continued stability in wholesale gas prices, I believe that energy suppliers should be seeking to regain the trust of consumers by reflecting this in their pricing decisions."
When speaking to the Daily Mail, she added: "Labour's price freeze was a theme for why they were unable to reduce prices before the election. Now that threat is no longer there, I intend to keep up the pressure on them to act.
"My focus is to get the best deal for consumers and the department is working hard to keep energy bills as low as possible."
Executive director of consumer group Which?, Richard Lloyd, said: "Energy firms have totally run out of excuses for not cutting our bills. It's good that ministers are acting but we now need to see suppliers do the right thing, and fast. If they don't play ball it will add weight to the case for the competition authority to step in and force the energy firms to make bills fair."