Former White House adviser Carl Icahn, pictured in 2015, resigned in August after criticism that his efforts to change the Renewable Fuels Standard would benefit an oil refining company he owns. | Neilson Barnard/Getty Images for New York Times Ex-Trump adviser Icahn subpoenaed by U.S. attorney over biofuels

The U.S. Attorney for the Southern District of New York has subpoenaed former White House adviser Carl Icahn for information about his push to change the federal biofuels program, according to a SEC filing issued by his company.

Icahn Enterprises L.P. says in the Nov. 3 10-Q filing that the U.S. attorney recently contacted it "seeking production of information pertaining to our and Mr. Icahn’s activities relating to the Renewable Fuels Standard and Mr. Icahn’s role as an advisor to the President."


President Donald Trump named his longtime billionaire friend as an unpaid "Special Advisor to the president for Regulatory Reform" in December, though Icahn resigned that position in August after drawing criticism that his efforts to change the RFS would benefit CVR Energy, an oil refining company he owns.

"We are cooperating with the request and are providing information in response to the subpoena," the filing says. "The U.S. Attorney’s office has not made any claims or allegations against us or Mr. Icahn."

Reports of Icahn's lobbying to alter the biofuels blending program — and the EPA's subsequent rejection of those changes — are believed to have driven fluctuations in the prices of biofuel credits that refiners must buy to show they are complying with the federal program.

Ethanol producers and some ethics experts complained that Icahn's push to change the federal program was a clear conflict of interest, and Senate Democrats sent letter to the SEC and CFTC demanding investigations.