ENERGY giant EDF prompted calls for greater transparency in pricing today as it posted a 7.5% increase in UK profits, just two months after an average 10.8% increasing its charges to 3.7million British households.

The French-owned group, which has plans to build a new nuclear power station at Sizewell, said that its £1.7billion profits haul in the UK had been driven by its generation arm, with its residential electricity and gas retail business remaining loss-making.

But Adam Scorer, director of policy at Consumer Focus, called for greater transparency between prices and profits in the utility sector.

“Greater transparency about industry costs and company profits is going to be critical if consumers are to have confidence in an energy market where prices just seem to go one way,” he said.

Revenues at EDF’s UK arm rose 6.4% to 9.7bn euros (£8.4bn) last year. The group said the increase in UK profits reflected a leap in generation output last year, including its best performance from nuclear operations in seven years and a 37% jump from its coal-fired plants, with rising wholesale prices also contributing.

The generation arm, which accounts for around 95% of UK earnings, has for some time been offsetting losses at its residential UK business, which fell into the red during 2011.

EDF added that it re-invested £1.3bn into its services and nuclear and coal stations last year, up £200m on 2011.

Vincent de Rivaz, EDF Energy chief executive, said: “Our financial performance last year enabled us to make significant investments in both our existing power stations and our plans for new nuclear stations in the UK, which will help keep the lights on in future with reliable, secure and low carbon energy.”

EDF announced in December it was extending the lifespan of its Hunterston and Hinkley Point nuclear plants by seven years to 2023.

The group is currently in talks with the UK government over investment for a new multi-billion pound nuclear reactor at Hinkley Point in Somerset, which is expected to cost around £7bn, with a similar development planned at Sizewell.

Energy group Centrica, which owns British Gas and a 20% interest in EDF’s eight existing nuclear power stations in the UK, recently announced that it would not be taking up an option to take a 20% stake in the Hinkley Point and Sizewell new-build proejcts.

Results for the wider EDF group showed the firm made 16.1bn euros (£13.8bn) in profits last year, up 7.7% on 2011.