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LAGOS, Nigeria (Reuters) -- Nigerian militants released four foreign oil workers on Monday, ending a 19-day hostage crisis that also saw Nigerian oil output cut by a tenth.
The hostages -- an American, Briton, Bulgarian and Honduran -- were abducted from an offshore oilfield in the southern Niger Delta on January 11, one of a series of attacks on the oil industry in the world's eighth largest exporter.
"They have all been released. They are all alive and well," said the spokesman for the southern state of Bayelsa.
The militants had demanded more local control over the delta's oil wealth, compensation for oil pollution to villages in the vast wetlands region and the release of two Ijaw leaders. The Ijaw are the biggest ethnic group in the delta.
Diplomats and militants said it was unlikely that the release of the hostages would mark the end of attacks on oil platforms and pipelines, which have forced Royal Dutch Shell to close 221,000 barrels per day of production.
"I think there will be more attacks," said a security consultant for a multinational oil company in Nigeria.
A militant Ijaw group with apparent links to the kidnappers sent an e-mail on Sunday agreeing to the hostages' release as a goodwill gesture to the international community.
"The Movement for the Emancipation of the Niger Delta has agreed to release the four hostages on humanitarian grounds as an offer of goodwill to the people of the world," said the statement, signed by imprisoned Ijaw militia leader Mujahid Dokubo-Asari.
The kidnappers had demanded freedom for Asari, who is standing trial for treason, as one condition for releasing the hostages.
A militant source involved in the negotiations said the government paid 100 million naira ($770,000) as a ransom to the kidnappers.
On Sunday, police said about 20 armed men stormed the headquarters of a South Korean oil services company in the delta and stole more than $300,000 in the latest attack on foreign firms. There were no casualties. (Full story)
The attack occurred only five days after nine men were killed during an attack on the offices of Italian oil company Agip, a unit of ENI. The attackers robbed a bank on the premises.
The militants' violent campaign has forced Shell to remove more than 500 employees from the delta.
Oil unions have threatened to withdraw from the delta, which produces almost all of Nigeria's 2.4 million barrels a day of oil, if security deteriorates further.
With oil markets nervous about tension between the West and Iran, the unrest in Nigeria's oil heartland has contributed to a rise in prices to four-month highs of more than $67 a barrel.