Nigeria frees Halliburton staff as probe continues

* Arrests relate to case involving former Halliburton unit

* Detained staff included Nigerians and expatriates

* KBR pleaded guilty last year to US charges it paid bribes

ABUJA, Nov 29 (Reuters) - Nigeria's anti-corruption police said on Monday employees of U.S. oilfield services group Halliburton (HAL.N) arrested last week in a bribery case have been freed, but must stay in the country pending further investigations.

The Economic and Financial Crimes Commission (EFCC) detained 10 Nigerian and expatriate Halliburton staff for questioning as well as one senior employee each from oil firms Saipem Contracting Nigeria Ltd (SPMI.MI) and Technip Offshore Nigeria Ltd (TECF.PA). [ID:nLDE6AQ0BH]

The arrests relate to a bribery case involving the U.S. firm's former unit KBR (KBR.N). The companies split in 2007 and Halliburton has said it is not connected with the case.

A spokesman for the EFCC said the detainees, taken into custody on Thursday, had been released because under law they could not be held for more than two days, but said they would remain in Nigeria until investigations had been completed.

"We can't keep them for more than 48 hours. Their travel documents have been detained pending the investigation ... they cannot leave the country," EFCC spokesman Femi Babafemi said.

Houston-based engineering firm KBR pleaded guilty last year to U.S. charges that it paid $180 million in bribes between 1994 and 2004 to Nigerian officials to secure $6 billion in contracts for the Bonny Island liquefied natural gas (LNG) project.

KBR and Halliburton reached a $579 million settlement in the United States but Nigeria, France and Switzerland have conducted their own investigations into the case. [ID:nN22234252]

Halliburton said it was not involved in the LNG development, its employees have never participated in any work on the project and the EFCC raid last week had no legal basis.

It said its offices were ransacked and personnel assaulted during last week's raid in what it described as "an affront against justice".

"What we are doing is based on fresh information," Babafemi said. "It is illogical to say we acted illegally. As long as the laws of the country are upheld there is nothing illegal in what we are doing."

A former aide to Nigerian ex-president Olusegun Obasanjo pleaded not guilty in October to six counts of money laundering in relation to the case between 2002-2003, including accepting $1.5 million in bribes. [ID:nLDE69C23V]

His case was adjourned to Dec. 16. (For more Reuters Africa coverage and to have your say on the top issues, visit: af.reuters.com/ ) (Reporting by Joe Brock; editing by Nick Tattersall/David Stamp)