Sir David King, the government's chief scientific adviser, believes 40 per cent of Britain's electricity should come from nuclear generation, twice its current contribution.

Sir David told the Financial Times that an "optimal" scenario would see Britain's entire "baseload" capacity coming from nuclear, with renewable energy sources providing a further 10-20 per cent of electricity.

The remainder would come from gas-fired power stations and "clean coal" facilities, which would bury carbon dioxide emissions underground.

Sir David emphasised he was voicing a personal opinion and that such a scenario would be subject to public acceptability.

"A possible scenario for the energy mix on the grid which could deliver competitive prices, a secure supply, and a significant reduction in carbon dioxide emissions would be up to 40 per cent from nuclear energy, used all year round for baseline supply; 10-20 per cent from renewables; and the remainder, only brought into play for peak demand, from gas and coal," he said.

The government is to conduct a wide-ranging energy review. The review will consider, among other things, whether Britain should build a new generation of nuclear power stations.

The proportion of power from nuclear sources has already fallen from 27 per cent to 20 per cent during the past few years. More of Britain's ageing reactors are being decommissioned. On current trends, all but one of Britain's nuclear power stations will be closed by 2023.

Sir David believes both nuclear power and renewable energy sources must be used together if Britain hopes to meet its target to reduce greenhouse gas emissions by 60 per cent by 2050.

Wind, waves and sun are increasingly seen as a prospective supply of carbon-free electricity. But the energy they deliver is too sporadic and unpredictable to rely upon for baseload. Conversely, the government sees problems with relying too heavily on nuclear generation.

"[Nuclear power] has the disadvantage that it cannot easily follow peaks and troughs in energy demand," the Department of Trade and Industry said in its energy review consultation document. "Were it to provide more than about 30 per cent of the UK's electricity, issues of overcapacity may arise at periods of low demand."

France, reliant on nuclear energy for more than three-quarters of its electricity, sells its excess to neighbouring countries. Britain has only a single electricity connection to continental Europe, limiting its scope to sell power abroad.