Interior Secretary Dirk Kempthorne will expand ethics oversight after reports revealing parties, sexual relationships and lavish gifts between U.S. government oil brokers and energy company employees.

Kempthorne told a House of Representatives panel Thursday that he would appoint an attorney-adviser in the Denver office at the center of the scandal. The office collects billions of dollars from oil companies drilling on federal lands.

Kempthorne also said he was considering terminating workers involved who are still employed with the agency.

Last week, in three separate reports, the Interior Department's inspector general alleged that 13 employees in Washington and Denver were rigging bids, accepting expensive gifts, and partying with oil company employees.