Shares in energy providers dipped in early trading, after the Competition and Markets Authority (CMA) outlined a raft of measures aimed at increasing competition in the energy market.
Shares in SSE fell 0.5 per cent to 1,566p while London-listed Centrica shares dropped 0.6 per cent to 265.9p, after a wide-ranging report attacked the UK's "Big Six" energy companies.
The CMA said most dual fuel households could save £160 a year by switching to a new energy provider. Electricity prices have risen 75 per cent in the last 10 years, while gas prices have been hiked 25 per cent – although it added that "much of the recent increases are down to increased environmental and related network investment costs".
The report added that measures introduced by the energy regulator, Ofgem, to encourage people to switch have been largely ineffective.
A lack of transparency in the market is "hampering trust", and can only be solved by "wider availability of financial imformation, more effective communication of the impact of decisions on bills, alongside a clear and transparent demarcation of responsibilities between the Department of Energy and Climate Change and Ofgem – and a clearer, independent role for Ofgem".
Roger Whitcomb, chairman of the energy market investigation, said consumers "don't have to" pay too much for their energy bills.
"Some energy suppliers know they don't have to work hard to keep these customers. It's notable that there are such high levels of complaints about customer service."
But despite Whitcomb's strong words,, analysts suggested the findings were less hard-hitting than expected.
"[The report] ties in with our view the unpalatable retail price increases that have been seen in recent years are, unfortunately ultimately justified, as they largely reflect external market pressures," said Whitman Howard utilities analyst Angelos Anastasiou.
"We still believe that the CMA’s findings will provide positive clarification that will be helpful to the companies."
Centrica chief executive Iain Conn welcomed the review.