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By Austin Ekeinde

PORT HARCOURT, Nigeria, Sept 27 (Reuters) - Gunmen disguised as soldiers killed a Colombian oil worker and abducted two other foreigners in Nigeria on Thursday in a raid on the construction yard of oil services company Saipem, authorities said.

The raid follows a threat on Sunday by rebel group the Movement for the Emancipation of the Niger Delta (MEND) to launch attacks on Africa's top oil producer following the arrest of one of its leaders in Angola.

MEND said in an e-mail to Reuters that its fighters were not involved in the attack, but that it could have been prompted by the threat.

"Some armed men came in boats, attacked Aker base where you have Saipem. The attackers killed one person and abducted two," said police spokeswoman Ireju Barasua in Port Harcourt, the delta's biggest city, where the yard is located.

About 10 gunmen, some dressed in military fatigues, exchanged fire with soldiers at the Saipem yard before escaping, private security contractors said.

Italian oil giant Eni <ENI.MI>, which controls Saipem, said a Colombian man was wounded in the attack and died shortly after being taken to hospital. It said another Colombian and a Filipino were missing after the raid.

MEND was responsible for a series of attacks in early 2006 that shut down about a fifth of oil production capacity from Nigeria, an OPEC member and the world's eighth biggest exporter of crude oil.

The group had observed a ceasefire since new president Umaru Yar'Adua took office on May 29 promising negotiations with delta rebels and a development plan to address the underlying problems of poverty, pollution, corruption and neglect.

But factional leader Henry Okah's arrest on arms dealing charges in Angola on Sept. 3 prompted the group to threaten renewed violence.

MEND says it is fighting for regional control over the mineral riches of the delta, where most people live in poverty. But the line between militancy and crime is blurred.

More than 200 foreign workers have been kidnapped since early 2006 and almost all have been released after the payment of a ransom.

A MEND spokesman who uses the pseudonym Jomo Gbomo said on Thursday their fighters were holding off on an attack pending the return to Nigeria of Yar'Adua from the United Nations, expected on Friday.

"We are expecting Yar'Adua to call his over-enthusiastic security agencies to order and use diplomatic channels to close this matter and let sleeping dogs to lie," he told Reuters in an e-mail with regards to Okah's arrest.

Asked if MEND was responsible for the Saipem raid, he said:

"We are not responsible for this attack. It may be as a result of our statement." (Additional reporting by Tom Ashby in Lagos)

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