Energy industry regulator Ofgem is to launch an investigation into how much suppliers are paying for wholesale energy.

Ofgem discovered a 27% difference in how much suppliers were paying for electricity and 15% for gas last year.

Wholesale prices are the reason quoted for the majority of supplier price rises.

Two weeks ago Scottish Power upped prices by up to 20%, and wholesale price rises were cited. British Gas are widely expected to raise prices in the next few weeks.

Ofgem has been shown new data that, contrary to the image portrayed by many large utility companies in the country, the data suggests suppliers are not paying the same prices on wholesale markets.

Ofgem’s data found that some suppliers are better at sourcing cheaper wholesale energy for re-selling to their consumers.

Ofgem said it is to hire accountants that will be looking further into suppliers’ accounts over the next few months.

Tim Yeo, chairman of the energy select committee, said: “I very much welcome this greater transparency. It reveals very different input prices and that some are much smarter at buying energy than others. It will mean consumers can see why they are made to pay higher prices by some companies so they can make judgments about which they would rather have as their supplier.”