BEIJING, June 8 -- Gunmen kidnapped five South Koreans in an overnight raid on a gas plant in southern Nigeria owned by Shell, the militants and officials from the company and Seoul's Foreign Ministry said Wednesday.

    Several Nigerian soldiers and one of the assailants were killed in a firefight during the raid, according to the Movement for the Emancipation for the Niger Delta, which claimed responsibility.

    MEND, the main militant group in Nigeria, has been responsible for a wave of attacks and abductions this year in the country's oil-rich southern delta. The militants say impoverished southern Nigerians aren't getting enough of the oil revenue.

    An official at the Nigerian arm of Royal Dutch Shell PLC said the hostages were working as contractors at the Shell plant near Nigeria's oil hub of Port Harcourt. Shell said it has shut down the plant, which has capacity of 150 million cubic feet of gas a day.

    The official, who spoke on condition of anonymity because he was not authorized to release the information, said the plant was attacked by gunmen but said he had no details on casualties.

    MEND indicated it wanted to exchange the hostages for the delta region's most prominent leader, Mujahid Dokubo-Asari, who has called for autonomy for southerners and was jailed last year on treason charges. His release has been a top militant demand since they took up arms this year.

    South Korea's Foreign Ministry said three of the kidnapped South Koreans worked for Daewoo Engineering and Construction Co., and the other two are from the state-invested Korea Gas Corp., the ministry said. A Nigerian was also kidnapped, South Korea said.

    The Koreans were "in good health and have been returned to one of our bases," the militants said.

    There were 14 South Korean workers at the site, but the other nine escaped and took shelter in a control room, the ministry in Seoul said.

    (Source: Shenzhen Daily/Agencies)