(Reuters) - The White House on Tuesday denied that President Donald Trump planned to issue an executive order to change the national biofuels program, after the U.S. Renewable Fuels Association (RFA) said Trump’s team had informed the group an order was pending.

File Photo: Truck driver Randy Walker fills his rig's tanks with biodiesel fuel at a gas station in the town of Nevada, Iowa, December 6, 2007. REUTERS/Jason Reed

Trading in U.S. refinery shares, fuel futures and corn prices was turbulent on the news of the pending order and its subsequent denial, as investors puzzled over what it would mean for the price of gasoline, ethanol and shares of companies that produce them.

The RFA issued a statement early on Tuesday that said a member of the Trump administration had called to inform the group the president intended to sign an executive order that would shift the onus on combining biofuels with gasoline away from refiners. The order would require companies further down the supply chain, such as retailers who sell gasoline, to shoulder that load.

Refiners have long requested this change, saying the biofuels program has hammered their profits.

White House spokeswoman Kelly Love, however, said on Tuesday afternoon “there is no ethanol executive order in the works.”

Ethanol and fuel retail groups reacted quickly to the reports. Trump’s regulation adviser, billionaire investor Carl Icahn, is majority owner of CVR Energy CVI.N, a refining company that would benefit from the change. That stock is up 80 percent since Trump's election in November.

Even after the White House denial, RFA Chief Executive Officer Bob Dinneen stuck by his statement, saying there is “certainly something in the works, but they’re not going to confirm it until they are ready to roll with it.” He declined to identify who in the Trump administration contacted the association.

“Despite our continued opposition to the move, we were told the executive order was not negotiable,” Dinneen said.

The Renewable Fuel Standard requires fuel companies to use increasing amounts of biofuel blended with gasoline and diesel. Former U.S. President Barack Obama expanded the rules, which started under his predecessor, George W. Bush, when gasoline prices were near records.

Refineries without operations designed to blend biofuels such as ethanol into gasoline have to pay for renewable fuel credits, known as RINs, to meet U.S. environmental standards to help reduce greenhouse gas emissions. The cost for refiners has increased sharply in the last few years; nine major publicly traded refiners paid $2.5 billion in 2016 for RINs costs, a 78 percent increase from 2015.

Among those that have pushed for the change is Icahn, who holds an 82 percent stake of CVR. That company’s shares jumped on Tuesday before paring gains after the White House denial; they ended up 3.5 percent on the day to $22.92 a share, on heavier-than-usual trading volume of 1.7 million shares.

Icahn was unavailable for comment, and CVR declined to comment.

Emily Skor, CEO of biofuel trade group Growth Energy, expressed concern about any role Icahn may have played in planning changes to the program.

“I assure you this is no deal for anyone but Carl Icahn,” she said. “If we had been approached with this deal, we would have flat-out rejected it.”

Seven Democratic senators, including Elizabeth Warren of Massachusetts, sent a letter to the White House this month, saying Icahn’s role as an adviser to Trump created financial conflicts of interest and called for a review.

Shares of U.S. refiner Valero VLO.N, which would also benefit from the changes, ended up 1 percent on Tuesday to close at $67.95 a share.

‘BACKROOM DEAL’

Biofuel organizations and groups representing fuel retailers and integrated oil companies like the U.S. units of Royal Dutch Shell Plc RDSa.L and BP Plc BP.L have opposed the change, which they say will complicate managing the program.

One source said the RFA was told the executive order would include incentives for ethanol and biodiesel in a tradeoff for the blending shift.

Those changes could include a waiver to allow greater volumes of ethanol to be blended into gasoline in the summer, a review of how the Environmental Protection Agency estimates emission impacts of biofuels, and support for a congressional tax credit for domestic producers of biodiesel, the source said.

Chicago Board of Trade corn futures Cc1 ended up about 1.7 percent. CBOT soyoil BOc1, which is used for biodiesel, rose 4.8 percent.

Compliance credits used to meet the annual biofuel blending standards traded around 43 cents on Tuesday from 47 cents to 48 cents previously, paring big morning losses.