MPs have questioned executives from the UK's six biggest energy companies over price rises after four of them recently hiked charges by between eight and 11 percent.
E.ON, British Gas, npower, EDF, Scottish Power and SSE were quizzed by MPs on the Energy and Climate Change Committee (ECCC). They were called in front of the ECCC to defend inflation-busting increases. Analysis by industry regulator Ofgem shows that, while the increases announced this autumn by some of the companies have averaged 9.1 percent, wholesale prices have risen by 1.7 percent adding just £10 to the average household bill of £600.
Christian MP Jeremy Lefroy told Premier's Tulika Pandey during the News Hour he wants to know how the companies can justify such rises.
The four firms involved have insisted that the rises were largely due to increasing wholesale prices and green levies. The former Conservative Prime Minister, Sir John Major, has called for a windfall tax on the firms.
But Guy Johnson, from npower, said a huge amount of money is being ploughed into infrastructure.
He said: "We've invested £2.9 billion in the UK over the last five years and that is 1.8 times are operating profit so each year we've invested £260 million more in the UK than our profit."
William Morris, from SSE, said they buy raw materials up to two years ahead, keeping wholesale rises stable at four per cent - which is actually good for consumers.
He said: "It is regrettable they are increased at all and of course none of us what prices to rise but I am optimistic that my business will remain in that four percent figure." E.ON has yet to announce a price rise and its chief executive Tony Cocker said the firm would "hold out as long as we can".
Mr Cocker told MPs he knows the companies are mistrusted by consumers: "I fundamentally belive that this market is competitive but we are not trusted and therefore, I believe, we need to have a very thorough competition commission investigation."
Stephen Fitzpatrick, who heads a smaller company - Ovo Energy - said he's mystified by the hikes: "Like some of the committee members I have been somewhat confused by looking at the explanations for the price rises in the past three or for four weeks from some of our competitors because we don't see nearly the same impact especially in wholesale quantity costs."
Previously, the Prime Minister has said that he wants to see further competition between suppliers. David Cameron said: "I'm frustrated about the big six. I want to see the big 60. I want to see many more energy companies."
Labour wants the government to take tough action against the so-called Big Six energy firms.
Leader Ed Miliband has pledge to freeze gas and electricity bills for 20 months if Labour wins the 2015 general election.