KBR has been among firms involved in reconstruction in Iraq
The former chief executive of US construction firm KBR, Albert Stanley, has pleaded guilty to charges of corruption relating to Nigerian deals.
Mr Stanley faces a seven-year prison sentence and must pay $10.8m (£6.07m), said the US Justice Department.
He and others were accused of gaining construction deals worth more than $6bn by bribing Nigerian officials.
KBR, which has caused controversy for its role in Iraq's reconstruction, had been part of Halliburton.
Mr Stanley was accused of breaching anti-bribery rules under the Foreign Corrupt Practices Act over a decade-long period.
"Today's plea demonstrates that corporate executives who bribe foreign government officials in return for lucrative business deals can expect to face prosecution," said Matthew Friedrich, acting assistant attorney general.
As well as criminal charges, the Securities and Exchange Commission (SEC) made civil charges against Mr Stanley.
Along with others involved in the scam, Mr Stanley "determined it was necessary to pay bribes to individuals within the Nigerian government in order to obtain contracts to build liquefied natural gas facilities in Bonny Island, Nigeria," said the watchdog.