The UK government's official climate change advisers have raised the bar on ambitions to cut emissions.

The Committee on Climate Change (CCC) said a cut in greenhouse gas emissions of at least 80% by 2050 should include international aviation and shipping.

It said other industries would have to make up any shortfall in those areas.

Prime Minister Gordon Brown has intimated at an 80% cut, but ministers have been wary of counting aviation and shipping, where cuts are difficult.

Mr Brown hinted at the Labour Party conference that the UK would need to cut emissions to just one fifth of the current amount - a task of staggering ambition.