WASHINGTON (AP) — Interior Secretary Dirk Kempthorne told Congress on Thursday that he is considering firing employees in his department's oil royalties office who investigators say were receiving lavish gifts, partying and having sexual relationships with oil company officials.

Kempthorne also told a House panel that he would appoint an attorney-adviser to oversee ethics in the Denver office at the center of the scandal. The office is responsible for marketing billions of dollars' worth of oil and natural gas that energy companies barter to the government in lieu of cash royalty payments for drilling on federal lands, a program known as Royalty-In-Kind.

"I can assure the committee that this process will be completed as swiftly as possible, and we will examine the full spectrum of disciplinary actions, including termination," said Kempthorne.