CUSTOMERS of Worcester-based energy giant Npower and the five other major power companies are paying up to £234 too much for gas and electricity every year, it has been claimed.

A report published by the Competition and Markets Authority yesterday, Wednesday, February 18, said 95 per cent of customers on dual fuel plans could save money by changing their tariff or supplier.

The organisation is currently conducting an extensive probe into the so-called Big Six power firms – Npower, Centrica, SSE, British Gas, EDF, Scottish Power and E.ON – with provisional findings due to be published in May.

Speaking on BBC Radio 4’s Today programme Liberal Democrat energy secretary Ed Davey said he would have no qualms about breaking up the Big Six companies if the report’s findings suggested this was an appropriate course of action.

In a statement he added the companies were treating customers “unfairly” by not offering them the best deals.

"My message for consumers is the same as these early findings - don't stick with a supplier if you're not satisfied,” he said.

“Now's the time to shop around for a better deal, switch suppliers and save."

The report also found the firms made 12 per cent more per unit for electricity and 13 per cent for gas from customers on joint tariffs than those on other deals.

The organisation is now set to look at why customers do not switch suppliers.

Executive director of consumer group Which? Richard Lloyd described the report as “a watershed moment for the energy market”.

"The Competition and Markets Authority now needs to develop a set of solutions to repair the market and make it work for everyone, not just the suppliers,” he said.

"This must include establishing a fair price that people can trust, to restore consumer confidence in the energy system.

"Consumers will also be looking to politicians of every party to set out how they'll deliver fair and affordable energy prices in the future."

The report comes after the energy regulator Ofgem referred the sector for a full-scale competition investigation last year.

Npower did not respond to requests for a comment.