WASHINGTON (Reuters) - A law firm representing small U.S. refineries has urged the Environmental Protection Agency to keep refiners’ applications for waivers from the nation’s biofuel policy secret from the Department of Agriculture, arguing that the petitions include confidential business information.

FILE PHOTO: The U.S. Environmental Protection Agency (EPA) sign is seen on the podium at EPA headquarters in Washington, U.S., July 11, 2018. REUTERS/Ting Shen/File Photo

The request, made by Perkins Coie in a letter to the EPA dated July 8, adds to mounting pressure from representatives of the refining industry for the Trump administration to box the USDA out of the controversial waiver program.

The letter follows Agriculture Secretary Sonny Perdue publicly expressing opposition to the way the program has been run in recent years.

The program can exempt small refiners in financial turmoil from their responsibility to blend ethanol into gasoline under the Renewable Fuel Standard. Waivers can save them tens of millions of dollars but are broadly opposed by the corn industry, which argues they undercut biofuel demand.

Since President Donald Trump took office, the EPA has roughly tripled the number of waivers it has granted to small refiners, drawing anger from the corn lobby and putting Trump in the middle of a battle between two powerful constituencies important to his re-election campaign.

In the letter to EPA Administrator Andrew Wheeler, Perkins Coie said the applications contained confidential business information (CBI) that should not be shared with the USDA.

“The USDA seeks the small refineries’ CBI in order to assert influence over EPA’s final decisions and thereby reduce the number of small refinery petitions granted by EPA. This interference is improper as a matter of law,” it said.

The letter added that refiners feared the USDA would share the confidential information in the applications with players in the agriculture community, which could undermine the refineries’ ability to compete.

“We would view any release of CBI to USDA as an indication that USDA was given improper influence over the decision-making process for small refinery hardship relief,” the letter said.

Last week, Republican senators representing oil states wrote to Trump asking him to keep Perdue away from any decision-making process over the petitions. Louisiana Senator John Kennedy also wrote to Perdue saying he will block confirmation of agency nominations until Perdue “stops interfering.”

Perdue has often sided publicly with farmers on the issue of biofuel waivers and told farmers at an event in Iowa recently that he had spoken to Trump about it and was helping to devise a fix. Trump has also ordered a review of the small refinery waiver program after hearing criticism from farmers during a recent tour of farm country.