HOUSTON (Reuters) - A coalition of U.S. state attorneys general received guidance from well-known climate scientists and environmental lawyers in March as some of them opened investigations into Exxon Mobil for allegedly misleading the public about climate change risks, documents seen by Reuters showed.

A sign is seen at the entrance of the Exxonmobil Port Allen Lubricants Plant in Port Allen, Louisiana, November 6, 2015. REUTERS/Lee Celano

Peter Frumhoff of the Union of Concerned Scientists, which has urged action on climate change, and Matt Pawa, who litigated against Exxon in a global warming case, were listed as presenters at a March 29 meeting of more than a dozen state prosecutors, according to emails between the offices of attorneys general in New York and Vermont.

The previously unknown level of coordination with outside advisers offered a glimpse behind the scenes in an increasingly pitched battle between Exxon and environmental groups.

Exxon has said it has been unfairly singled out and that climate activists are conspiring to rally public opinion against it.

Environmental groups are pushing in court, at the U.S. Securities and Exchange Commission and in the offices of pension funds to demand more accountability on climate issues from big oil companies.

Shortly after the March 29 private meeting, 17 attorneys general and former Vice President Al Gore announced that they would work as a coalition to push for more aggressive action on climate change. The statement did not reference conversations with outside groups.

Participating in the meeting and in the statement were 15 state prosecutors plus two more from the District of Columbia and the U.S. Virgin Islands.

The attorneys general from Massachusetts and the U.S. Virgin Islands said they would start climate-related investigations against Exxon, adding to probes underway in New York and California.

The documents also suggested that the state attorneys general are at least pondering using the powerful anti-racketeering RICO law if a company is shown to have mislead the public over climate change.

State lawyers are already investigating possible violations of securities and consumer protection laws.

Some of the state lawyers at the meeting considered inviting Sharon Eubanks, a former Department of Justice official who successfully sued tobacco companies under RICO, winning a multi-billion dollar settlement, according to the emails. Eubanks said she did not attend the meeting.

Frumhoff confirmed that he was at the meeting. Pawa declined to comment. The New York attorney general’s office said it routinely collaborates with other states and receives input from outside organizations but only pursues cases based on their merits and the law. Vermont’s office did not immediately comment.

The emails were obtained through open records requests filed by the Energy & Environment Legal Institute, a free-market think tank with ties to the Competitive Enterprise Institute, whose website says it opposes U.S. Environmental Protection Agency regulation of greenhouse gas emissions.

The Energy & Environment Legal Institute gave Reuters access to the documents.

State prosecutors have opened probes into Exxon based on reports last year by Inside Climate News and the Columbia Journalism School that said the company’s in-house scientists had flagged concerns about climate change decades ago, only to have them doubted or contradicted by executives.

Exxon, which said it now believes the threat of climate change is real and warrants action, has said those stories “wrongly suggested that we had reached definitive conclusions about the risks of climate change decades before the world’s experts and while climate science was in an early stage of development.”

Inside Climate News and Columbia have stood by their reports.

In addition to the inquiries by states, Exxon faces pressure from investors concerned with sustainability to disclose more about the risks climate change poses to its business.

Lee Wasserman, a director of the Rockefeller Family Fund, which has urged divestment from fossil fuels, said coordinating around climate issues is healthy.

“In America, when civic associations come together to address pressing societal concerns, that is considered a good thing - not a conspiracy,” Wasserman said.