Nuclear power may have to be embraced in a bid to combat climate change even though it is not a "sustainable" energy source, Margaret Beckett has admitted.
Nuclear energy provides 20% of Britain's electricity
The environment secretary said she was very reluctant to build new nuclear power stations, but that she had "accepted that it could happen".
But Mrs Beckett said any investment in nuclear must not be at the expense of renewable energy sources.
An energy policy review is set to be announced early this week.
In an interview with ITV1's The Jonathan Dimbleby Programme, Mrs Beckett was questioned about her view that nuclear power is not a sustainable energy source.
"I don't think you can argue that it meets the definition of sustainability," she stressed.
"But that's a separate issue from saying, however, despite those enormous problems, you're driven to it by other considerations such as climate change and I've always accepted that that could happen."
Nuclear power currently meets about a fifth of Britain's electricity needs, but that is set to fall to just 4% by 2010 when old power stations are decommissioned.
Mrs Beckett's comments come as a report in the Sunday Times suggested the government's chief scientific adviser Sir David King wants to put a levy on consumers' energy bills to fund a new generation of power stations.
Liberal Democrat environment spokesman Norman Baker said: "Rather than increasing fuel costs to pay for nuclear the government should be investing in renewable energy."
A Department of Trade and Industry spokesman said the government's policy was to carry out a review which looked at the entire energy mix.
"There is no silver bullet to meeting our objectives and we will continue to look at a mixture of energy sources including use of fossil fuels and developing renewable energy as well as energy efficiency measures.
"We will also examine the options for civil nuclear power and whether and to what extent we should replace the existing generating stations that will reach the end of their lives over the next 30 years."
Any further use of nuclear power would require an extensive public debate, he added.
Green group Friends of the Earth said research showed many potential sites for new nuclear power stations are at risk from sea level rises.
It called on the government to drop any idea of building new plants.