Prime Minister Tony Blair has given his strongest signal yet that he backs the building of a new generation of nuclear power stations in the UK.
Mr Blair has raised the prospect of new nuclear power stations
The prime minister told the CBI annual dinner that the issue was "back on the agenda with a vengeance".
He said Britain faced the prospect of being largely reliant on foreign gas imports for its future energy needs.
Critics claim Mr Blair had decided to opt for nuclear power even before the government energy review launched.
In the speech Mr Blair revealed he had seen a "first cut" of the government-commissioned energy review, due by the end of July.
Chairman of the Sustainable Development Commission Jonathon Porritt said: "It would be damaging to this government's credibility if it were to pre-empt the conclusions of its own energy review, by making premature and insufficiently considered announcements on nuclear power."
The commission, which is the government's independent watchdog on sustainable development, recently produced a report that said nuclear power was not the answer to tackling climate change or security of supply.
Ahead of the speech, Mr Blair's official spokesman predicted there would be "despairing shrieks of outrage" in response to the prime minister's comments.
BBC political editor Nick Robinson said ministers appeared to be considering changes to the planning process to overcome local resistance to new power stations.
Meanwhile, BBC political correspondent Carole Walker said she believed Mr Blair had been happy to stir up a "whole storm of controversies" this week, on issues such as animal experimentation.
She said the prime minister wanted to show he was ready to take on controversial decisions.
She said: "He cannot afford to be seen as somebody who is simply languishing in Number 10 while people are waiting for his days to be over.
"He is trying to distract from all the speculation there is about when he is going to go."
A Department of Trade and Industry spokesman said there was as yet no first draft of the energy review, and that the prime minister would be responding to information about its progress passed on to him by Energy Minister Malcolm Wicks.
The prime minister said if current policy remained unchanged there would be a "dramatic gap" on targets to reduce CO2 emissions by 2025 forcing Britain to become heavily dependent on gas.
"We will move from 80 or 90% self-reliance on gas to 80 or 90% dependency on foreign imports, mostly from the Middle East, Africa and Russia," he told business leaders.
These "stark" facts "put the replacement of nuclear power stations, a big push on renewables and a step change on energy efficiency, engaging both business and consumers, back on the agenda with a vengeance," Mr Blair added.
For the Conservatives, shadow industry secretary Alan Duncan accused Mr Blair of "trampling" over the review in his desire to reassert his authority in government.
Stephen Tindale, spokesman for environmental group Greenpeace, said: "The prime minister obviously made up his mind about nuclear power some time ago, and certainly well before the government launched its energy review.
"The review is a smokescreen for a decision that has already been taken."
'Does not make economic sense'
CND chairwoman Kate Hudson argued: "Nuclear power does not make economic or environmental sense. The amount of money invested in producing nuclear power could produce far more sustainable energy, much more rapidly."
Friends of the Earth's Tony Juniper meanwhile said: "It's probably no coincidence that a number of nuclear sceptics were removed from key Cabinet posts earlier this month."
Liberal Democrat leader Sir Menzies Campbell said Mr Blair had made his mind up to support new nuclear power stations.
"The economic case for nuclear is extremely weak. There are many other options for a secure low carbon energy supply."
He said Mr Blair would present a large nuclear tax bill to future generations and described the move as another "desperate attempt" to establish a legacy.