According to leaked documents, the Department for Transport (DfT) is briefing UK members of the European Parliament to oppose amendments to regulations on cutting carbon dioxide from cars which would require a tough new target for new vehicles from 2025.
Greenpeace scaled a five-storey building in Lewes, East Sussex, in transport minister Norman Baker's constituency, to unfurl a banner claiming he is blocking the proposals put forward by fellow Liberal Democrat Fiona Hall, representing the European Parliament's Industry, Research and Energy Committee.
The amendments to the regulation governing cuts to carbon emissions from cars up to 2020 would mean the inclusion of a long-term CO2 reduction target for 2025, potentially 70 grams per kilometre on average across the fleet. The current targets require manufacturers to reduce average carbon emissions for new cars to 130g/km in 2015 and 95g/km in 2020.
Greenpeace also says the DfT is supporting measures which would enable car makers to over-count the number of electric vehicles they are producing to allow other cars to produce more emissions.
Campaigner Sara Ayech said: "These documents reveal that there is a split at the heart of the Liberal Democrats over policy to reduce carbon emissions and save motorists money. Norman Baker should follow the progressive lead of Fiona Hall and support laws that will help the environment, whilst putting an average of £400 a year back into the pockets of hard-pressed motorists."
A DfT spokeswoman said: "It is important to strike the right balance by supporting ambitious targets while ensuring we do not hinder industry growth or competitiveness and encourage continued investments in low-carbon vehicle technologies in the EU."
"Beyond 2020, it is likely that some form of mandatory targets will continue to be an effective measure for reducing CO2. We would only consider specific targets following a (European) Commission review and assessment of the impacts to ensure that target levels were ambitious, but realistic and based on sound evidence."
Ms Hall, MEP for North East England, said: "Norman Baker and I are both committed to further reducing CO2 emissions from cars. But whereas the DfT wants to wait to look at specific targets until after the Commission's review next year, I would like to send a political signal right now that the 2025 target must be ambitious."