There were also issues to be resolved in relation to nuclear waste, the government said in a progress report following the publication last year of a White Paper setting out national energy policy for the next 50 years.

"Before any decision to proceed with the building of new nuclear power stations, there would need to be the fullest public consultation and the publication of a White Paper setting out the government's proposals," the government said.

Britain has not built any nuclear power stations for more than a decade and most of its reactors are scheduled to close over the next twenty years.

British Energy (BGY.L: Quote, Profile, Research) , the country's biggest power generator, which operates most of the country's nuclear plants, was recently bailed out by the government after slumping electricity prices pushed it to the verge of bankruptcy.

Prospect, the UK's largest trade union for engineers, called on the government to re-open the nuclear debate immediately.

"On most projections of present policies, the UK will be unable to close the carbon gap created by the loss of nuclear generation, even before the impact of the European Union's emissions trading scheme," said Paul Noon, the union's general secretary, in a statement.

Monday's government report said the UK was on track to miss its self-imposed target of reducing CO2 emissions unless it beefed up current policy.

"We will have to review existing policy measures and assess the potential for strengthening these and introducing new ones to meet our climate change objectives..." the government said.

Britain has set itself a goal of a 20 percent cut in CO2 emissions by 2010, from 1990 levels. Current projections foresaw a reduction of 13-14 percent over that period, the government said.

"Our environmental targets have become more challenging," said the government. Economic growth was expected to be higher than originally forecast and recent CO2 emissions had risen, mainly because power stations had burned more coal than expected, it added. However, the UK was on course to exceed its commitments on greenhouse gas emissions under the Kyoto protocol. The UK is joining the European Union's emissions trading scheme which start in January as part of the bloc's strategy to cut CO2 emissions in line with its Kyoto targets.

The government is relying on a huge expansion of renewable power sources such as wind turbines to help curb emissions.

It is also working hard to boost the country's energy efficiency. Earlier this week, ministers unveiled plans for a "step change in energy efficiency", which they said would save three billion pounds a year on energy costs and help bring down CO2 emissions within the next six years.

Britain must juggle its aims of reducing CO2 emissions with the need to secure future energy supplies as its North Sea reserves of gas start to dwindle. Analysts expect the UK to become a net importer of gas before the end of the decade.

The government said the development of new gas import projects needed to accelerate. "Whilst the transition to importing gas has led to a number of infrastructure projects...these have been slow to go forward," it said.