Halliburton Co. (HAL) on Friday severed ties with the former chairman of its KBR (search) engineering and construction unit, accusing him of receiving "improper personal benefits."

Halliburton said it terminated ties with A. Jack Stanley, who retired in December as KBR chairman, and another former employee, who was not identified, for violating its code of conduct. The two most recently worked for the company as consultants.

Stanley could not be reached for comment. Halliburton gave no details of the benefits received by Stanley and the other former employee.

Halliburton is involved in a dispute with the U.S. government over whether KBR overcharged for work in Iraq and Afghanistan, but the accusations against Stanley are related to a project in Nigeria.

Halliburton said the improper benefits came to light during a probe of payments made by a joint venture in connection with a natural gas liquefaction plant project in Nigeria.

The U.S. government is investigating the payments made by the joint venture, TSKJ, to the Nigerian government, Halliburton said last week.

Halliburton, once run by Vice President Richard Cheney, said it is cooperating with the U.S. Department of Justice and the Securities and Exchange Commission (search) and is continuing with its own internal probe.

The company said it does not believe it has violated the Foreign Corrupt Practices Act (search). But it said it plans to ask TSKJ to terminate immediately all services of TSKJ's agent, Tri-Star Investments.

TSKJ is a Portugal-registered consortium owned equally by KBR, Technip SA of France, Eni SpA affiliate Snamprogetti Netherlands, and JGC Corp. of Japan.

Nigeria in February said it was investigating allegations that the consortium paid $150 million to $180 million of kickbacks to secure a contract to build the LNG plant.

Last year a French magistrate opened a probe into the payments.

In May 2003 Halliburton disclosed it owed as much as $5 million in taxes to Nigeria. An internal audit discovered that one of its overseas units paid $2.4 million to an entity owned by a Nigerian national to get favorable tax treatment in the oil-rich West African country, according to the company.

Shares of Halliburton were down 33 cents, or 1 percent, at $29.87 on the New York Stock Exchange (search).