The new stations are expected to be built with private sector help to ensure the future security of supplies and a balanced energy "mix", amid mounting global concern over long-term oil and gas provision and cost.

"Set against the challenges of climate change and security of supply, the evidence in support of new nuclear power stations is compelling", Business Secretary John Hutton told parliament in a widely-expected announcement.

The move, applauded by unions and business leaders, follows call from the pro-nuclear lobby for an early decision as most of the 19 reactors at Britain's 10 existing nuclear power stations, will close by 2023.

The plants provide 19 percent of Britain's electricity.

But opponents, with strong concerns over waste and safety, question whether atomic energy can help cut carbon emissions and want greater clarity on costs, plus assurances that consumers will not have to pay for eventual decommissioning.

Greenpeace last year won a legal challenge after complaining the government's consultation process was flawed. The group said it was studying closely the re-ordered consultation and had not ruled out fresh action.

The group, Friends of the Earth, Britain's third party the Liberal Democrats and the Green Party all want more emphasis on sustainable or renewable energy like wind, wave and tidal power.

According to government figures, five percent of Britain's electricity came from sustainable sources in 2006. The government proposes to increase that to 15 percent by 2015.

Greenpeace executive director John Sauven described Thursday's announcement as "bad news".

"Nuclear power can only deliver a four percent cut in emissions some time after 2025, and that's too little too late at too high a price," he said.

"We need energy efficiency, cleaner use of fossil fuels, renewables and state of the art decentralised power stations like those in Scandinavia. That's the way to defeat climate change and ensure energy security."

Hutton sought to address those concerns, saying nuclear power had been a "tried and tested, safe and secure form of low-carbon technology" for more than 50 years, and was more efficient and cost-effective than coal-fired stations.

Safety would be the top priority but he said it would be wrong to set a target for the amount of electricity to be produced by nuclear or any other form of low-carbon energy.

New plants were likely to be built on or near existing sites, he added, but failed to specify an exact number. Recent media reports here have suggested Brown is in favour of 10 new reactors.

He also made no mention of cost. The Guardian newspaper last July said six reactors could cost as much as 12 billion pounds (16 billion euros, 24 billion dollars) for six plants.

Hutton said the costs for developing, building, operating the new plants -- which he hoped could be running by 2020 -- and disposing of nuclear waste would be met by energy companies, not the taxpayer.

The government would help with reforms to the planning process to fast-track applications, he added.

Britain's announcement follows a growing trend towards nuclear around the world.

About 16 percent of the world's electricity comes from nuclear power. In the European Union, the figure is 30 percent, rising to 75 percent in France and 55 percent in Belgium.

About 440 nuclear reactors are operational globally, with a further 28 under construction and another 62 planned.