(Recasts with another claim of responsibility) By Tom Ashby ABUJA, Oct 22 (Reuters) - All seven hostages seized by gunmen from an offshore Nigerian oilfield were released on Monday after two days in captivity, a state government spokesman said. "All seven have been freed. They are in a government house," said Ebimo Amungo, a spokesman for Bayelsa state government, where the kidnapping had taken place. The four Nigerians, a Briton, a Russian and a Croat were all in good health. The attack on Shell's EA field was the first big raid on an oil facility since President Umaru Yar'Adua took office in May and the government worked fast to ensure it did not derail a nascent peace initiative in Africa's top oil producing region. The attack had no immediate impact on oil output because the field was halted after an earlier militant attack in February 2006. It had been expected to resume production of 115,000 barrels per day (bpd) by the middle of next year. A spokesman for a prominent militant group, the Movement for the Emancipation of the Niger Delta (MEND), claimed responsibility for the abduction. However, industry and security sources said the claim did not ring true. It was more likely an attempt by a delta warlord to gain relevance with local authorities, they said. The line between militancy and crime is blurred in the impoverished delta, a vast area of mangrove-lined creeks and swamp. Militants also engage in crime, often in cahoots with government officials, civil society groups say. More than 250 foreign workers have been kidnapped over the past two years and almost all have been released after payment of ransom. When Yar'Adua took office, he promised to address the grievances of militants whose attacks and kidnappings have cut Nigerian oil output by a fifth and driven away thousands of foreign workers. They are demanding greater regional control over oil revenues, jobs and development. The two sides are expected to hold a formal peace conference before the end of the year and the kidnapping was seen as potentially a major setback. Industry officials said the raid on EA may delay the field's restart, but that it was unlikely to affect Shell's plans to resume operations in the rest of the western Niger Delta, which accounts for another 360,000 bpd and was also closed in early 2006.
