Energy firm EDF has announced a price hike for its gas and electricity.
From November 10, gas will by 15.4 per cent more expensive, and electricity tarrifs are to rise by 4.5 per cent, the company said on Thursday morning.
EDF's price increases come a month after energy company British Gas announced they were hiking up prices by 18% and in the week where the CPI index of inflation rose to 4.5%.
Shadow energy secretary Meg Hillier said the energy market was "unaccountable".
"It's with sickening inevitability that we see the last of the big six raise its prices. This is a much lower increase in electricity than the other energy companies which begs the question of why EDF can raise the price less than others.
"The energy market is an example of an unaccountable concentration of power. Six energy companies control 99 per cent of the market. Ed Miliband has made it clear that we need to see more competition and more transparency. Ensuring the market is free and fair is vital if we are to bring bills down.
"Hard-hit families have nowhere to go whilst the Tory-led Government sit on their hands."
Richard Lloyd, executive director of consumer watchdog Which?, said many people would "struggle to heat their homes this winter" as energy companies raise their prices.
“All of the major suppliers have now announced substantial price hikes, so now is the time to make sure you’re on the cheapest available deal," he said.
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