A Greenpeace investigation has identified a little-known, privately owned US oil company as the paymaster of global warming sceptics in the US and Europe.

The environmental campaign group accuses Kansas-based Koch Industries, which owns refineries and operates oil pipelines, of funding 35 conservative and libertarian groups, as well as more than 20 congressmen and senators. Between them, Greenpeace says, these groups and individuals have spread misinformation about climate science and led a sustained assault on climate scientists and green alternatives to fossil fuels.

Greenpeace says that Koch Industries donated nearly $48m (£31.8m) to climate opposition groups between 1997-2008. From 2005-2008, it donated $25m to groups opposed to climate change, nearly three times as much as higher-profile funders that time such as oil company ExxonMobil. Koch also spent $5.7m on political campaigns and $37m on direct lobbying to support fossil fuels.

In a hard-hitting report, which appears to confirm environmentalists' suspicions that there is a well-funded opposition to the science of climate change, Greenpeace accuses the funded groups of "spreading inaccurate and misleading information" about climate science and clean energy companies.

"The company's network of lobbyists, former executives and organisations has created a forceful stream of misinformation that Koch-funded entities produce and disseminate. The propaganda is then replicated, repackaged and echoed many times throughout the Koch-funded web of political front groups and thinktanks," said Greenpeace.

"Koch industries is playing a quiet but dominant role in the global warming debate. This private, out-of-sight corporation has become a financial kingpin of climate science denial and clean energy opposition. On repeated occasions organisations funded by Koch foundations have led the assault on climate science and scientists, 'green jobs', renewable energy and climate policy progress," it says.

The groups include many of the best-known conservative thinktanks in the US, like Americans for Prosperity, the Heritage Foundation, the Cato institute, the Manhattan Institute and the Foundation for research on economics and the environment. All have been involved in "spinning" the "climategate" story or are at the forefront of the anti-global warming debate, says Greenpeace.

Koch Industries is a $100bn-a-year conglomerate dominated by petroleum and chemical interests, with operations in nearly 60 countries and 70,000 employees. It owns refineries which process more than 800,000 barrels of crude oil a day in the US, as well as a refinery in Holland. It has held leases on the heavily polluting tar-sand fields of Alberta, Canada and has interests in coal, oil exploration, chemicals, forestry, and pipelines.

The majority of the group's assets are owned and controlled by Charles and David Koch, two of the four sons of the company's founder. They have been identified by Forbes magazine as the joint ninth richest Americans and the 19th richest men in the world, each worth between $14-16bn.

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

Greenpeace accuses the Koch companies of having a notorious environmental record. In 2000 the Environmental Protection Agency (EPA) fined Koch industries $30m for its role in 300 oil spills that resulted in more than 3m gallons of crude oil leaking intro ponds, lakes and coastal waters.

"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.

A spokeswoman for Koch Industries today defended the group'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," said a statement sent to AFP by Melissa Cohlmia, director of communication. She added: "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."

Top 10 Koch beneficiaries 2005-2008

Mercatus center: ($9.2m received from Koch grants 2005-2008) Conservative thinktank at George Mason University. This group suggested in 2001 that global warming would be beneficial in winter and at the poles. In 2009 they recommended that nothing be done to cut emissions.

Americans for prosperity. ($5.17m). Have built opposition to clean energy and climate legislation with events across US.

Institute for humane studies ($1.96m). Several prominent climate sceptics have positions here, including Fred Singer and Robert Bradley.

Heritage foundation ($1.62m). Conservative thinktank leads US opposition to climate change science.

Cato Insitute ($1.02m). Thinktank disputes science behind climate change and questions the rationale for taking action.

Manhattan Institute ($800,000). This institute regularly publishes climate science denials.

Washington legal foundation ($655,000) Published articles on the business threats posed by regulation of climate change.

Federalist society for law ($542,000) advocates inaction on global warming

National center for policy analysis ($130,000) NCPA disseminates climate science scepticism.

American council on science and health ($113,800) Has published papers claiming that cutting greenhouse emissions would be detrimental to public health.