Koch Industries, a huge privately-owned US company dominated by oil and chemical interests, is plowing millions of dollars into campaigns to discredit climate science and clean energy policies, a report alleged Tuesday.

Between 2005 and 2008, the Kansas-based conglomerate that "most Americans have never heard of" spent nearly 25 million dollars to fund "organizations of the 'climate denial machine,'" environmental protection group Greenpeace said in the report.

Between 2006 and 2009, Koch Industries and the family that founded and still controls the conglomerate spent 37.9 million dollars on direct lobbying on oil and energy issues -- eclipsed only by oil majors Exxon and Chevron, who spent 87.8 million dollars and 50 million dollars, the report said.

"Although Koch intentionally stays out of the public eye, it is now playing a quiet but dominant role in a high-profile national policy debate on global warming," the report says.

Greenpeace published a list of 35 organizations and 21 lawmakers who have directly or indirectly received funds from Koch Industries, the company's affiliates, or foundations set up by the Koch family.

They include conservative think-tank the Cato Institute, which got more than one million dollars in grant money from Koch; and grassroots group Americans for Prosperity, which is campaigning to block the Environmental Protection Agency from regulating greenhouse gases.

That group got over five million dollars.

Koch has also contributed to politicians, the report said, listing 17 Republicans and four Democrats whose campaign funds got more than 10,000 dollars from the company.

A foundation set up by Charles Koch, who with his brother controls the US conglomerate, partly funded a report published in 2007 that said polar bears were not endangered by climate change, the report said.

And at least 20 Koch-funded organizations have repeatedly broadcast and referenced the "Climategate" scandal, in which emails were leaked from University of East Anglia scientists in Britain that said climate change was not as serious a problem as previously thought.

"The combination of foundation-funded front-groups, big lobbying budgets, political action campaign donations and direct campaign contributions makes Koch Industries and the Koch brothers among the most formidable obstacles to advancing clean energy and climate policy in the US," Greenpeace said.

Representatives of Koch, meanwhile, were audibly surprised to learn about the report and its allegations from AFP, and a spokeswoman for the company defended Koch's track record on environmental issues.

"Koch companies have consistently found innovative and cost-effective ways to ensure sound environmental stewardship and further reduce waste and emissions of greenhouse gases associated with their operations and products," a statement sent to AFP by Melissa Cohlmia, director of communication, said.

"Based on this experience, we support open, science-based dialogue about climate change and the likely effects of proposed energy policies on the global economy," said the statement, which was sent to AFP before Koch Industries had seen the report.

Koch Industries, the family and foundations bearing the name "support economic freedom and market-based policy solutions," the statement added.

"These efforts are all about creating more opportunity and prosperity for all, as it's a historical fact that economic freedom best fosters innovation, environmental protection and improved quality of life in a society."