Exclusive: U.S. senators call for probe into coal export sales WASHINGTON (Reuters) - Two top U.S. senators are calling for the Interior Department to investigate whether coal companies stand to short taxpayers hundreds of millions of dollars on export sales. Democratic Senator Ron Wyden, the incoming chairman of the Energy and Natural Resources Committee, and the panel's leading Republican, Senator Lisa Murkowski, said they were concerned that coal companies may be shorting royalty payments. At issue is mining in the vast Powder River Basin in eastern Wyoming and Montana which is coal rich and chiefly on federal land. Mining companies pay a royalty to extract fuel from that region. The lawmakers cite a Reuters investigation into how companies like Arch Coal Inc, Peabody Energy Corp and Cloud Peak Energy Corp account for royalties on sales to Asia from the Powder River Basin. "If any violations of the law have occurred, companies should be required to cure any gap in royalty payments and, if misconduct has occurred, civil penalties should be levied," a letter from the lawmakers sent on Thursday to Interior Secretary Ken Salazar reads. Reporting By Patrick Rucker; Editing by Andrea Ricci