Ministers who campaign for greener roads are still driving 'gas-guzzlers'

Official figures reveal that the Department for Transport agency providing the vehicles has failed to meet its carbon dioxide emission target two years running. And just eight out of a fleet of 200 official cars are environment-friendly "hybrids" which can run on petrol and electricity, according to the latest annual reports.

The figures emerged as Alistair Darling, Secretary of State for Transport, hosted the Environmentally Friendly Vehicles Conference in Birmingham where representatives of governments and industry met to discuss ways of promoting greener vehicles.

While Mr Darling was driven from the railway station to the conference centre in a Ford Focus using bio-fuels, his usual ministerial car is a Rover 75 which uses standard petrol. Mr Darling told the conference: "Taking action to tackle climate change is essential ... I am determined that transport should play its part in addressing the threat of climate change."

Tom Brake, transport spokesman for the Liberal Democrats, said it was time the Government led by example. "Action speaks louder than words. Here we have Alistair Darling banging on about renewable fuels at a when the Government is failing to keep its own house in order. This is hypocrisy. It's time the Government led by example and boosted the fuel efficiency of its own fleet." A Department for Transport statement in June urged ministers to adopt hybrid vehicles. Six of the eight "hybrids" are now used by ministers, including Elliot Morley, the environment minister. As part of Mr Darling's "green" strategy, he revealed an initiative to force oil companies to explore renewable energy sources.

Under the Renewable Transport Fuel Obligation suppliers of petrol will have To ensure that five per cent of sales come from renewable sources from 2010.

Mr Darling said "carbon savings" could increase in the years after 2010, depending on how the level of obligation changed.

He said: "This will help reduce the impact of transport on climate change and increase the UK's fuel security and diversity of supply." To ensure biofuels were "sourced sustainably", companies would have to report on the level of carbon savings achieved and on the sustainability of their supplies, Mr Darling said.

Stephen Joseph of Transport 2000 welcomed Mr Darling's initiative but called on the Government to go further. Mr Joseph argued that yesterday's announcement was too small to catalyse the change that was needed to tackle greenhouse gas emissions. Ministers also needed to reduce traffic, encouraging more integration between transport systems.