英国能源公司大幅提高天然气价格和电价

It may proved to be a moment of revelation. These Big Six power companies have been called before Parliament to shed some light on rising customer bills. The regulator Offgem says gas may not be rising as fast as they claim.

-They do have to pay these green levies for government policy reasons, they are going up dramatically. And also the transmission and distribution costs are going up dramatically. Wholesale cost, no. But other cost, yes. Unfortunately the main reasons is that because we are in a free market, because they all report to stock market, they must make more profit year on year to keep the bosses in the jobs.

British Gas, SSE, Scottish Power and En Power have raised household bills by an average of 9.1% for this winter. They all say mounting wholesale costs are to blame. But Offgem data show these prices have only gone up by 1.7% over the past year. And that should only add 10 pounds to each bill.

-MPs want energy bosses to justify these recent winter price hikes but also to detail the difference in their pricing plans and to explain how profits can be made more transparent in the future. Executives have been called to appear before a committee here tomorrow.

-It's a global market at the end of the day and something as far removed(?) as the Fukushima disaster has had a big impact on UK gas prices. Japan has shut down nuclear reactors. They are more dependent on gas than ever. They are more willing to pay for it. So in the global market, the UK needs to compete. And those prices have reflected that.

Yet here at home, smaller firms like the Co-op have kept hikes in check. Unlike the Big Six, they are absorbing the cost of wholesale market moves themselves.

-Their duty is to their shareholders first and foremost and to return profits to their shareholders. Our duty in running this business is to our customers because they are the people who own our business. And that's the fundamental difference.

But one after the other, the big power firms all listed the same reasons for hiking rates: green levies, infrastructure investment and the cost of wholesale fuel. Now increaslingly, that equation doesn't seem to add up. What's clear is a lack of transparency on how energy firms make all their money has left customers in the dark for too long.

Poppy Trobert, Sky News.