A fresh scandal over climate change has erupted in the United States after leaked documents appeared to show a right-wing funded campaign to influence how climate science is taught in schools.

The internal budget and strategy documents from a Chicago-based non-profit group called the Heartland Institute were made public last week, and showed $200,000 was to be spent on a "global warming curriculum project."

The project would teach that "whether humans are changing the climate is a major scientific controversy" and that climate models' "reliability is controversial," according to some of the leaked documents.

Others showed hundreds of thousands of dollars in donations from fossil fuel industries and interests, an anonymous donor's pledge of $1.25 million, and $300,000 to be paid to a team of scientists to rebut UN findings on climate change.

The Heartland Institute has said that one of the leaked strategy memos, a two-page document, was fabricated, but has not commented on the others and did not respond to AFP requests for an interview.

The scandal appeared to take on larger dimensions Wednesday when a lawmaker called for a hearing into whether one of the scientists named in the documents, a government employee, had improperly accepted payments from Heartland to spread the anti-climate-change message.

Indur Goklany, assistant director of programs, science and technology policy at the Department of the Interior, was named as being allocated $1,000 per month to write a chapter on economics and policy for the Heartland Institute.

The chapter was to appear in a book produced by the group's "Nongovernmental International Panel on Climate Change (NIPCC), an international group of scientists that produces critiques of the reports of the United Nations' IPCC."

A Democratic congressman from Arizona, Raul Grijalva, requested a full hearing of the Natural Resources Committee, noting that it is unclear whether Goklany received payments -- which is illegal for federal employees -- or if other government scientists were involved.

"Our Committee has a unique responsibility to find those answers," Grijalva wrote. His appeal is awaiting a decision by senior lawmakers.

Another government contractor, David Wojick at the Department of Energy, has drawn scrutiny for his alleged links to the group after documents showed he would be paid $25,000 quarterly for his work in drafting the school curriculum.

Wojick is listed as a "senior consultant for innovation" at the DOE's Office of Science and Technological Information.

Greenpeace USA sent a series of letters to the government urging an official inquiry into whether the documents reveal illegal payments to government scientists and a conflict of interest.

The documents show Heartland, which was founded in 1984, has "a coordinated multimillion dollar, multi-year campaign to sow confusion about climate change and climate change science," Greenpeace USA research director Kert Davies told AFP.

Another wrinkle emerged in the story on Monday when a prominent climate scientist admitted he had posed as a Heartland board member to fraudulently obtain copies of the confidential internal documents and distribute them to colleagues and the media.

Peter Gleick, president of the Pacific Institute, said his involvement began early this year when he "received an anonymous document in the mail describing what appeared to be details of the Heartland Institute's climate program strategy."

Gleick said he then "solicited and received additional materials directly from the Heartland Institute under someone else's name," which "confirmed many of the facts in the original document."

Gleick apologized late Monday, adding: "My judgment was blinded by my frustration with the ongoing efforts -- often anonymous, well-funded, and coordinated -- to attack climate science and scientists."

The blogosphere has been jammed with commentaries on his actions, alternately blasting Gleick for poor ethics or hailing him as a hero.

Heartland Institute president Joseph Bast said the group was seeking legal counsel, accused Gleick of a "crime" and added: "A mere apology is not enough to undo the damage."

Greenpeace's Davies said the revelation "has sort of made everything uglier," but should pass.

"Yesterday... it was, 'Oh my goodness, a scientist stole some documents,' but you know, we will get over that because the truth is -- what really happened was that he verified that the documents were real and they were from Heartland."