The new Environment Secretary David Miliband has said he is "open-minded" on the issue of nuclear power.
David Miliband says he wants to cut carbon emissions
He said no option should be taken off the table when looking at ways to cut harmful greenhouse gas emissions.
The government is currently considering building new nuclear plants as part of a review of Britain's energy needs.
But it faces opposition from environmentalists and its own advisory panel which has warned against a nuclear "quick fix".
Mr Miliband's appointment in last week's Cabinet reshuffle - replacing Margaret Beckett who was known to be sceptical about nuclear power - was widely seen as clearing one obstacle to building more nuclear plants.
His appointment means he will go head-to-head on green issues with Conservative leader David Cameron, who has made the environment one of his top priorities.
Mr Cameron's environment policy adviser Zac Goldsmith is known to be vehemently opposed to nuclear power.
But the Tory leader has refused to be drawn on the issue, urging voters to wait for the outcome of an internal Tory policy review.
He recently told The Independent: "I'm neither dogmatically in favour of nuclear power, nor dogmatically against.
"The most important thing is to set a framework which brings forward the least cost, least environmentally damaging ways of achieving the twin objectives of any sensible energy strategy: security of supply, and tackling climate change.
"We'll have more to say on this when we publish the conclusions of our own energy review in the next few months."
The Liberal Democrats are against building new nuclear plants.
Liberal Democrat Shadow Environment Secretary, Chris Huhne MP said: "While Mr Miliband's acknowledgment of the scale of the climate change challenge is welcome, his comments on nuclear power are worrying. "Not only does nuclear cause a great threat to the environment through the large amounts of waste produced, but it is also economically unviable."
He said the government should spend any money earmarked for nuclear subsidies on the "development of genuinely sustainable technologies".
Mr Miliband has said it would be wrong to rule out nuclear power in the government's energy review when it offered a way of reducing emissions.
"I am open-minded about how we meet the climate change challenge," he told BBC Radio 4's Today programme.
"Obviously the benefit of nuclear power is that it emits zero carbons but obviously there are costs associated with nuclear power and there are also waste issues, which are very important.
"If you believe that climate change is the number one issue facing the planet, which I do, it seems to me I cannot come and say 'by the way, I have taken off the table one way in which to generate power in a zero carbon way'."
Mr Miliband emphasised that he was committed to tackling climate change and warned that dealing with the issue would mean far-reaching change to the way people lived.
"If we are going to meet the challenge of climate change, no part of British life is going to be untouched, whether it be in government or in business or in individual life," he said.
"I would say the challenge of environmental sustainability is as big a challenge in the 21st century for people on my side of politics as the drive for social justice was in the 20th century.
"Throughout the 20th century people from the progressive side of politics established a social contract, a welfare state, to bring forward social justice.
"In the 21st century we need to establish an environmental contract that is as enduring, as deep, as the social contract that was established."