The power stations could be built within three years if their private sector owners decide to take the gamble on power prices remaining relatively high. But power companies, including Innogy and Centrica, have been reluctant to put funds into their construction until there are signs that energy prices have stabilised.

The reluctance of the generating companies to build the new gas power stations underlines the difficulty of persuading private contractors to build nuclear power stations without any subsidy.

Alan Johnson, the new Secretary of State for Productivity, Energy and Industry, is this week expected to begin addressing the question of supplying Britain’s future energy needs. He will look closely at whether the country needs to begin building new nuclear power stations to replace those that supply a fifth of the UK’s electricity needs, and has been advised by officials to reach a conclusion before the summer recess.

The potential capacity that could be provided by the gas power stations will have to be considered by the DPEI officials when they scrutinise how much new power generating capacity Britain needs over the next 35 years. Gas power stations are cheaper to build initially, but cost more to run than nuclear power while gas and oil prices are high.

Industry experts believe that private companies will opt to build modern gas plants, which emit lower amounts of carbon than older plants, before they consider building nuclear stations. Britain’s oldest nuclear power stations will begin to close next year, with five due to close by 2010, removing about 3,394 megawatts of generating capacity.

The DPEI is concerned that there is an increased risk of an electricity supply shortage after 2008, by which time four plants will have closed. At the same time the UK will become increasingly reliant on imported gas supplies.

Permission for the power stations was given in 2000, at the tail end of the energy boom that saw a flood of overseas investors, including the failed giants Enron and TXU, take positions in the UK’s liberalised energy markets. However, only two of the proposed power stations are being given serious consideration by their owners at this time. Centrica, which yesterday reported that wholesale gas prices had leapt by 40 per cent since the turn of the year, is closest to building the first of the proposed power stations. In March it invited tenders for a 1,010 megawatt plant at Langage in Devon.

The parent company of British Gas has said that it wants to assess the full cost of building the £400 million power station before it makes a decision later this year. Bankers estimate the cost of constructing nuclear stations at between £1.3 million and £1.7 million per megawatt capacity, compared with £340,000 for gas.

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