They are questioning a government drive to produce 10 per cent of the nation's electricity from renewable sources within 12 years, and are blocking the only official fund used to support it.
Only two weeks ago, John Battle, the energy minister, was hailing the fund as proof of the Government's "long-term commitment to encouragement for renewables". The stand-off threatens to escalate into a row between Gordon Brown, the Chancellor of the Exchequer, and Peter Mandelson, the new Secretary of State for Trade and Industry (and Mr Battle's boss) - adding fresh fuel to an already incendiary relationship.
Set up by the last government, the fund - the Non Fossil Fuel Obligation (NFFO) - gets its money from the addition of about 1 per cent to electricity bills.
Since 1990, the cash has been helping to finance 995 projects for windpower, hydropower and other renewable sources.Reuse content