Recent price rises by gas and electricity firms are not justified and the Competition Commission should investigate, a watchdog has said.
Three of the UK's "big six" energy firms have put up prices
Three energy companies have raised their prices by an average of 15%, affecting 27 million consumers.
They blame soaring wholesale energy prices but Energywatch says the market is not competitive enough and consumers are paying over the odds.
Regulator Ofgem insists that the UK energy market is competitive.
Energywatch says it is impossible to calculate how much excess profit energy suppliers are making because they are not transparent about what they pay.
Allan Asher from Energywatch told BBC News 24 that the entire energy market should be reviewed by the Competition Commission.
He said: "The price rises we've seen are not justified.
"There'll be more, but sadly the market is not working well and that's leading to consumers paying much, much more than they need to."
HAVE YOUR SAY
The UK market is dominated by six providers - Npower, EDF and British Gas are the companies which have recently raised their prices and rivals are expected to follow suit in coming weeks.
Use less energy and the cost of your bills will fall like lead balloon
Maga Nosferatu, Sussex
British Gas, the UK's biggest power provider, announced that it would increase the amount it charges for gas and electricity by 15%.
The move followed increases by Npower, which raised its electricity prices by 12.7% and gas by 17.2%, and EDF Energy, which put up its electricity tariffs by 7.9% and gas bills by 12.9%.
The National Consumer Council warned last year that the government's target to end fuel poverty amongst vulnerable consumers by 2010 may be missed.
The NCC said unless energy suppliers were forced to reduce prices for low income consumers then fuel poverty numbers would not fall.
But Russell-Hamblin Boone from the Energy Retail Association insisted that the prices set by energy companies were fair.
"We have the most competitive market in the world, and it's important to recognise that there are lots of additional costs as well as just the wholesale price cost that are now being incorporated into our bills," he added.