The kickback allegations involve KBR's contract to supply U.S. troops in Iraq, not its separate contract to rebuild Iraqi oil facilities and deliver gasoline to civilians. Pentagon auditors are seeking a criminal probe into findings that KBR and Kuwaiti firm Altanmia Marketing Co. overcharged by $61 million US for fuel deliveries. Halliburton has denied overcharging on that contract. Friday's disclosure is the first admission by Halliburton that its employees were involved in possible corruption involving Iraq contracts.