UK (The Guardian) – Ministers could save £12bn of public spending over four years by clamping down on tax breaks and support for polluting oil exploration, cement, aluminium and transport, according to a report from green campaigners this week.

With all three major parties are committed to cutting the projected £178bn budget deficit, and to a low-carbon economy, a report by the high-level Green Alliance thinktank argues that many spending cuts could achieve both ends. Perhaps the most controversial suggestion is to halve the £10bn national and regional roads spending budget.

Other proposals include ending the zero value-added tax (VAT) rate for aviation and shipping, and reducing tax breaks on oil and gas exploration and the Climate Change Levy for big energy users such as cement and aluminium companies, saving more than £5bn.

The report also says government departments should step up energy-efficiency improvements for buildings and vehicles to save £1.5bn over the four years, about one eighth of what they spend on fuel.

The challenge of meeting government efficiency savings was also revealed last week by the latest figures from the Department for Energy and Climate Change showing that public-sector emissions rose 6.5% in 2008, despite a 2% fall nationally.

The three major environment and conservation charities that commissioned the report – WWF, the The Royal Society for the Protection of Birds and Greenpeace – argue that it would be "reckless" to ignore the report.

Doug Parr, Greenpeace's chief scientist, said: "Britain can be a world leader in renewable technologies and low-carbon transport but only if we stop bailing out the dirty industries of the 20th century."

David Norman, WWF's head of campaigns, said: "The hole in the country's finances means, inevitably, that measures to support the environment and tackle climate change will come under pressure.