A new report has criticised the implementation of price control removals in the electricity, gas, telecom and postal markets.

According to the National Audit Office (NAO), introducing competition in these markets since 2002 has thus far failed to benefit poor consumers, with the watchdog citing complex tariffs that are not easily understood by some people as problematic.

Findings in the report come in the wake of the chancellor's decision to threaten the energy industry with the prospect of legal action unless they control the tariffs paid by millions of pre-payment customers.

Head of the NAO Tim Burr said: "The removal of price controls is an important step in the development of competition in these markets, but it is not the end of the story.

"Ofcom, Ofgem and Postcomm need to be vigilant, and be prepared to use their other powers when necessary, to ensure genuine competition is present and that it is working to serve consumers."

Regulators were urged to continue to protect the customer and focus on the advantages that competition can bring.

However, the report says: "Some consumers, particularly those classified as vulnerable, are still unable to take full advantage of the competitive market for a variety of reasons, including complex tariffs and a lack of easily accessible, trustworthy, relevant, understandable and comparable information."