The proposal, which is known as the 'Renewable Transport Fuels Obligation' was put forward at the Environmentally Friendly Vehicles Conference in Birmingham, where representatives from international governments and industry met to discuss ways to promote greener vehicles.

Darling said, "Taking action to tackle climate change is essential. The Renewable Transport Fuels Obligation I am proposing today is predicted to save around 1 million tonnes of carbon dioxide emissions in 2010 - the equivalent of taking 1 million cars off the road. Carbon savings could also increase in future years. This will help reduce the impact of transport on climate change, and bring environmental benefits for us all."

The Government also published the results of a feasibility study today, setting out how the obligation will work. It will require the major oil companies and importers to ensure that a growing proportion of their fuel sales are from a renewable source.

To ensure that biofuels are sourced sustainably, the Government proposes to develop a carbon and sustainability assurance scheme as part of the obligation. Obligated companies would be required to report on the level of carbon savings achieved and on the sustainability of their supplies.

Whilst biofuels are indeed a step in the right direction, it would be simply impossible for the UK to completely replace conventional diesel with fuel produced from biomass alone. For this reason it's the Government's intention to investigate further the potential for hydrogen fuel in the UK.

On this subject, Darling was hopeful, "In the longer term, we need to look seriously at the fuels we are using to power our transport which is why we are piloting the development of hydrogen fuelled transport. As a next step, we need to have a hard look here in the UK at the practical steps we would need to take to build a hydrogen infrastructure."