Energy firm bosses have agreed a number of measures aimed at reducing household energy bills after a summit meeting at which David Cameron told them action was "absolutely vital".
Millions of customers will receive letters offering advice on how to reduce costs by switching to different payment methods and taking advantage of free or subsidised insulation.
Suppliers have also agreed to put a message on bills this winter encouraging people to check whether rivals offer a better deal and to provide better information to help them switch.
Chief executives of the "Big Six" suppliers were brought together with consumer groups and watchdog Ofgem to discuss concerns over price rises with ministers.
The Prime Minister told them it was "absolutely vital" that consumers struggling already with rising food and petrol prices were not also hit by higher fuel bills.
Ministers were determined to be seen taking action on the issue after Labour leader Ed Miliband made tackling the "rigged" energy market one of his key policies.
Mr Miliband said at the weekend that firms should use soaring profits to cut "crippling" bills after figures suggested annual profits per customer had risen to £125 - from just £15 in June.
Those figures, produced by Ofgem, were disputed by suppliers.
Speaking afterwards, Mr Cameron said: "We are making energy companies be competitive.
"They're permanently being watched by Ofgem to make sure it is a competitive market, and we are making them make their energy available so that others can come in and provide customers with a good service."