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.

KBR was charged with five counts, including conspiracy to violate the Foreign Corrupt Practices Act (FCPA).