The Trump administration has denied a request from Exxon Mobil to waive U.S. sanctions against Russia and allow it to resume oil drilling around the Black Sea.

Treasury Secretary Steven Mnuchin says in a brief statement that the administration "will not be issuing waivers to U.S. companies, including Exxon, authorizing drilling prohibited by current Russian sanctions."

The decision comes just two days after it was reported that Exxon was seeking a waiver to resume a joint venture with Rosneft, a Russian state-owned oil company.

The request presented an unusual potential for conflicts of interest, given that Secretary of State Rex Tillerson was Exxon's CEO immediately before taking the Cabinet position. He lobbied against the sanctions after they were imposed in 2014, in response to Russia's annexation of Crimea.