Prime Minister Gordon Brown will be advised today that the target Tony Blair signed up to this year for 20% of all European energy to come from renewable sources by 2020 is expensive and faces "severe practical difficulties".
Britian currently produces just 2% of its energy from renewables.
Secretary of State for business John Hutton, is expected to tell Brown that Britain should work with governments sceptical about climate change to lobby German for lower renewable targets in December.
Hutton has warned the Prime Minister that boosting Britain’s renewable power to 9% of energy output – well below the European Union target – will cost £4bn.
Hutton is likely to suggest that nuclear power will help Britain meet CO2 targets, although he is wary of a fresh legal challenge from Greenpeace over its nuclear consultation. The first consultation into nuclear was declared inadequate under judicial review, following a Greenpeace challenge.
Green Party Principal Speaker and MEP Caroline Lucas said, "The Government has failed to show any real commitment on targets set by the EU, so the contents of these leaked papers sadly come as no surprise.
"Current government policies in support of renewable energy are confusing, piecemeal and inadequate, and now seem to be in complete disarray," she said.
The Liberal Democrats have attacked the Energy Minister, Malcolm Wicks, undermining the same target.
Wicks last night said that Britain would only aim to generate 10-15% of its electricity from renewables by 2020. "It is now clear," said Huhne, "that the Government is trying to backtrack on its promise to generate a fifth of our electricity from renewables by 2020.
"The promise was clearly made by David Miliband, and it is dishonest to suggest that the 20% target agreed at the Brussels summit should not apply to Britain."