HAL Halliburton Co.

LAGOS (AFP)--Nigeria's anti-graft agency said Thursday it was questioning suspects in a multi-million dollar cash-for-contract scandal embroiling U.S. giant Halliburton Co (HAL) and three former heads of state.

Justice Minister Michael Aondoakaa has flown to Washington to seek U.S. cooperation in getting the names of Nigerian officials implicated in the scandal, a spokesman for the Economic and Financial Crimes Commission said.

The country's attorney general has already written to his U.S. counterpart for a list of the names, media reports said this week.

Nigerian media and non government organizations said three former Nigerian presidents, Olusegun Obasanjo, Abdulsalami Abubakar and the late Sani Abacha were among those who accepted bribes in the scandal.

They also named a former petroleum minister Dan Etete and the former head of the national oil company Gaius Obaseki.

U.S. authorities announced in February that Halliburton and its former subsidiary Kellogg Brown and Root LLC had agreed to pay $579 million in fines related to the case, the biggest fines ever paid by U.S. companies in a foreign corruption case.

Halliburton, which will have to pay the bulk of the fine, admitted it had paid $182 million to Nigerian government officials over a 10-year period as part of a joint venture to win a $6 billion contract to build a liquified natural plant on Bonny Island.

"We invited some people for questioning and they are assisting in our investigations," the EFCC's Femi Babafemi told AFP.

Babafemi refused to identify the suspects, but said the agency was waiting for material evidence on the scandal.

KBR Inc (KBR), which was spun off by Halliburton two years ago, was part of the venture awarded four contracts between 1995 and 2004 to pipe raw natural gas to a specially built plant and convert it to liquified gas.

The probe centered around TSKJ, a private company registered in Portugal comprising Technip SA (TEC.FR) of France; Snamprogetti Netherlands, an affiliate of the Italian group ENI SpA (E); JGC Corp (1963.TO) of Japan and KBR.