But former KBR parent Halliburton said last month it would pay $559 million to end the investigation if the government approved the settlement, which was the largest penalty against a US company for bribery charges under federal law.

The alleged bribes were paid between 1994 and 2004 to secure four contracts for a KBR joint venture to build and expand Nigeria's Bonny Island liquefied natural gas terminal, according to the government.