The comments come as industry experts warn that the UK will shortly become a net importer of energy and Whitehall officials openly admitting that the dispute with Iraq has more to do with energy security than weapons of mass destruction.

In its upcoming report, the IPPR warns that a program of new nuclear reactors would reduce rather than enhance diversity because a series of reactors would have to be constructed to bring down capital costs over time. The IPPR argues this places too large a proportion of Britain's energy generation eggs in one basket.

"Were a serious fault later discovered with the AP1000 [reactor] or another reactor system that was used, then in a worst-case scenario all of the series might need to be taken offline while tests were carried out," the IPPR said.

With most nuclear Magnox stations due to close by 2010, the Trade and Industry Secretary, Patricia Hewitt, is said to be studying the extent to which nuclear power is essential to protect the security of British energy supplies.

It is understood that she is leaning towards treating renewable sources, such as wind power, as an economic and reliable substitute.

Adding to the debate, the forthcoming IPPR report argues that neither the industry nor government have done enough to allow for the risk of a terrorist attack on Britain's nuclear power stations.