International development agency Christian Aid has accused the Government of "eviscerating" the Climate Change Bill by failing to include within it a number of measures crucial to the fight against global warming.

Christian Aid said it was deeply disappointed at the Government's refusal to include a target for cutting UK carbon emissions of 80 per cent over 1990 levels by 2050, revealed by Minister of State for the Environment Phil Woolas at the start of the Bill's second reading in Parliament.

The agency warned that the credibility of the UK's climate change policies would be "fatally" undermined if steps to ensure that UK greenhouse gas emissions do not exceed the level necessary to limit global temperature rises were removed from the Bill.

It also roundly condemned the dropping of amendment agreed in the House of Lords that would have made it mandatory for publicly listed companies in Britain to declare their annual carbon emissions.

Another disappointment, Christian Aid said, was the failure of the Bill to ensure that at least 70 per cent of its targets would have to be met through emission cuts within the UK, rather than by purchasing carbon off-sets from poorer countries.

Sarah Spinney, Christian Aid's climate change campaigns manager, said: "The Government has eviscerated a piece of legislation that should have seen Britain blazing a trail internationally over combating climate change."

She added that the Government's "entire commitment to tackling climate change is now open to question".

"Instead of the UK setting an example of the measures needed to combat global warming, the lofty sentiments uttered by Government ministers in recent months have apparently been just empty words. The campaign for a Bill with real teeth will continue," said Ms Spinney.

She warned that only carbon emission cuts of 80 per cent and above would keep global temperatures below 2oC.

"That target is essential as beyond 2oC the effects of climate change such as drought, floods and disease will become rampant," Ms Spinney added.

The amendment on mandatory reporting, tabled by the Liberal Democrats and Labour backbench peers, followed pressure from a coalition of MPs, businesses and non-governmental organisations led by Christian Aid. UK businesses fund up to 15 per cent of carbon emissions around the world.

Under the Companies Act, large UK companies have a responsibility to provide a business review with their annual reports, including information on the social and environmental implications of their work. The amount of information given, however, is left to the company directors' discretion.

The amendment would have obliged any company producing a business review to include a statement on their greenhouse gas emissions. Whilst most companies do reveal some information on their emissions, Christian Aid said that the information was often provided in a way that made a true assessment of their activities "impossible".

The Bill would have also introduced enabling powers to give the Secretary of State power to issue mandatory guidance on greenhouse gas reporting. At a Confederation of British Industry (CBI) conference last year, 82 per cent of delegates voted in favour of mandatory standards on carbon emission reporting. In addition, the CBI Climate Change task force report calls for mandatory standards to be introduced in the short term.

Christian Aid added that countries such as the UK, where major industrial CO2 emissions first began, should help finance clean development in poorer countries on top of their cuts at home, rather than instead of such cuts.