NEW YORK (Reuters) - Lawyers for a group of teenagers suing the U.S. government in a climate change case have asked the government and the oil industry’s leading trade group to turn over emails sent and received by U.S. Secretary of State Rex Tillerson using an alias address while he was running Exxon Mobil.

U.S Secretary of State Rex Tillerson looks on during a joint press conference with Chinese Foreign Minister Wang Yi (not pictured) at Diaoyutai State Guesthouse in Beijing, China, March 18, 2017. REUTERS/Lintao Zhang/Pool

“It’s possible that Rex Tillerson was communicating with people in government related to climate and energy policy using that email address,” Julia Olson, a lawyer for the teenagers, said on Monday, referring to the alias address

Wayne.Tracker@exxonmobil.com.

Tillerson left Exxon Mobil Corp, where he had been chief executive and chairman, in December, and also stepped down then as chairman of industry trade group the American Petroleum Institute.

New York Attorney General Eric Schneiderman’s office, which is probing whether Exxon misled shareholders and the public about climate change, wrote to a judge last week accusing the company of not previously disclosing the alias and Tillerson’s communications through it.

Exxon said in response to the attorney general’s letter that the use of the alias was “entirely proper” and was aimed at giving priority to emails from a group of senior executives.

The teenagers’ case, filed in federal court in Oregon, seeks to prove government officials and oil industry leaders knew about the causes and effects of climate change but nevertheless carried on with policies that perpetuated it, violating Americans’ constitutional right to live in a habitable climate.

The federal government has argued in court filings that there is no support for the claim that Americans are constitutionally entitled to a protected climate, while the API has said climate science is not firmly established enough to support the teenagers’ case.

Spokespeople for the Justice Department, Exxon and the API did not immediately respond to requests for comment.

“Based on evidence we already have, it’s pretty clear that Rex Tillerson, Exxon and API all knew that climate change was very significant and was being caused by burning fossil fuels,” Olson said. “To the extent that we can get information through Wayne Tracker emails that they were openly acknowledging climate change was a big problem and trying to influence the government on how to deal with it, that helps our case.”

The case is Juliana v. U.S., U.S. District Court, District of Oregon (Eugene), No. 15-cv-01517.