With a 100 million-pound budget to drive Britain's move to a low carbon economy, the Trust achieved a reduction in emissions of between 1.2 million and two million tonnes between 2006 and 2007. That means it is on course to meet its 2010 target of 4.4 million tonnes, but with Britain's carbon dioxide emissions for 2007 at 543.7 million tonnes, the committee said there is plenty of work to be done to get businesses to cut emissions.

"This target is a small contribution in the context of increasing global energy costs and increased public awareness of climate change," said committee chairman Edward Leigh in a statement.

"The Carbon Trust could deliver more, but further progress depends upon contacting greater numbers of organisations without a corresponding increase in costs or a breach of the European State Aid rules."

The Committee of Public Accounts report said the Trust's work is made harder because small businesses remain unconvinced that energy efficiency makes commercial sense.

"The Carbon Trust also needs to overcome the reluctance of some senior business executives to prioritise emissions reductions as a business issue," added Leigh. "The Carbon Trust must provide evidence to the contrary and also aim to assist more eligible small businesses under its interest free loan incentive scheme."

Tom Delay, Chief Executive of the Carbon Trust responded: "Far from being 'small beer', by 2010 our work with business will, every year, be saving more than the entire current carbon emissions of Glasgow."

"Furthermore, our work generates significant cost savings for business too. Our work last year alone will generate direct cost savings to business of up to 650 million pounds."

A climate change bill currently going through parliament and expected to become law within three months sets the government a legally binding target of cutting emissions of carbon dioxide by 26-32 per cent by 2020 and 60 per cent by 2050.