Gordon Brown has been challenged to prove his green credentials by blocking plans to build Britain's first coal-fired power station for 24 years.
Environmental activists condemned a decision by councillors to support an application to demolish an outdated plant in Kent and replace it with another that burns coal, widely regarded as the dirtiest fossil fuel.
The final decision on allowing the development of the proposed station at Kingsnorth, near Rochester, lies with the Government.
Greenpeace warned that approval of the 1bn scheme would make a mockery of Britain's long-term commitment to cut carbon emissions. John Sauven, its executive director, said: "Gordon Brown recently promised this country he would lead the fight against climate change. Well, very soon we will know if he meant it.
"The proposal for a new coal-fired power station that has now landed on his desk represents what could be the defining climate-change decision of his premiership."
Under the application, two units using cleaner coal would be developed by the energy company E.ON UK. The company says the new plant, which could supply 1.5 million homes from 2012, would be more efficient than its predecessor and would cut carbon emissions by almost two million tonnes a year, the equivalent of taking 500,000 cars off the road. Despite nearly 9,000 objections, Medway council gave its support to the application, which has been passed to the Government for a final decision.
Given its sensitivity, Mr Brown, who is already considering a call from advisers to endorse the development of up to eight coal-fired stations, is bound to take a close interest.
The Independent disclosed last month that James Hansen, an authority on climate change, is urging the Prime Minister to veto plans to develop a new generation of coal-fired power plants. In a letter to Mr Brown, he warned that approving them would undermine the Bali agreement on global warming and discredit his commitments to reduce greenhouse gases.
Mr Hansen, the director of the Nasa Goddard Institute for Space Studies, in New York, warned that coal presented the biggest problem in combating climate change because governments seemed determined to use it as a cheap source of energy without considering the long-term consequences to the planet.
Robin Webster, an energy campaigner for Friends of the Earth, condemned the council's decision to back plans for an "outdated and dirty" power station. He said: "If built, Kingsnorth power station will undermine the Government's commitment to meet European targets for producing 20 per cent of energy from renewables by 2020.
"If it is serious about tackling climate change, the Government must throw out this proposal and promote investment in clean and green alternatives."
Christian Aid appealed to the Government to impose a moratorium on all such schemes. Andrew Hogg, its campaigns director, said: "The Government's public stance will be seen as empty rhetoric if Kingsnorth gets the go-ahead and ushers in a new generation of coal-fired power stations."
E.ON UK expects to win the Government's approval, and a spokesman said it hoped the power station, the first developed in Britain since 1984, would become the UK's first clean-carbon demonstration plant, with carbon from it captured and stored in depleted oilfields under the North Sea.
A new generation?
Kingsnorth is the only scheme for a new coal-fired power station to have reached the planning application stage so far. Energy companies, which have identified a series of sites across the country for a new generation of similar plants, are awaiting the decision over Kings-north. RWE npower has proposals to replace its coal-fired station at Tilbury in Essex by 2013. The company is also considering developing a plant at Blyth, in Northumberland. Scottish and Southern Energy is conducting a feasibility study into replacing one of two units at its Ferrybridge power station in West Yorkshire. ScottishPower is proposing developing clean coal plants at Longannet in Fife and Cockenzie in East Lothian. E.ON UK, which owns Kingsnorth, is considering building a coal-fired power station at High Marnham, Nottinghamshire. An old plant on the site closed in 2003 after more than 40 years of operation.