(Updates death toll) By Tom Ashby LAGOS, Jan 17 (Reuters) - An armed attack on an oil industry boat in Nigeria's southern Niger Delta in which a Dutch worker and two Nigerians were killed was a robbery, security sources said on Wednesday. A senior foreign oil industry executive said Tuesday's attack by 16 gunmen dressed in military fatigues, who sprayed automatic fire into a small boat ferrying staff of South Korean company Hyundai Heavy Industries, was symptomatic of a slide into anarchy in Africa's oil heartland. A Dutch oil worker and a Nigerian navy rating died during the ambush on a river between regional capital Port Harcourt and the Bonny Island oil and gas complex, and the Nigerian boat captain died later of his wounds, the Nigerian police said. "The motive of the attack was to steal a large sum of money in the boat," a military source said, adding it was likely that information about the transport of funds had been leaked from inside the Korean company. "I am sure we will catch those behind it," said the source, who did not wish to be named. Violence is intensifying in the Niger Delta, home to Africa's biggest oil industry, and has already forced Western multinationals to withdraw thousands of foreign workers and reduce the OPEC member nation's oil output by a fifth. Foreign oil workers are rarely killed in the delta, although they are often kidnapped for ransom or by militants pushing for greater regional autonomy. A militant group holding three Italians and one Lebanese said on Wednesday it had opened talks with the government on releasing the oil workers and that one sick Italian could be freed later on Wednesday. "We may release the sick one as early as today if all goes well, but I do not see the rest being released within the next two weeks," a spokesman for the Movement for the Emancipation of the Niger Delta said in an e-mail to Reuters. They were snatched from the Brass River oil export terminal operated by Italian oil company ENI <ENI.MI> on Dec. 7. ELECTION FEARS Many expect violence to escalate across Nigeria in the run-up to a general election in April, especially in the delta where political office comes with control over a big slice of the nation's oil revenue. "I think we will see more of this over the next few months. Less integration, more anarchy," said a senior oil executive. Tuesday's attack was apparently unrelated to a spiralling communal conflict at a nearby community in Rivers state where 12 people were killed on Sunday, prompting oil companies to evacuate three oilfield stations. Royal Dutch Shell <RDSa.L> reduced output by 12,000 barrels per day at one of the fields on Tuesday. Rivers state is in the eastern side of the Niger Delta, where multinationals evacuated hundreds of workers' dependants last month after two car bombings in oil company compounds in the state capital Port Harcourt. Foreign companies had already pulled out thousands of workers from the western delta after a wave of militant attacks last February that cut Nigerian output by at least 600,000 barrels per day. Security in the delta has deteriorated drastically over the past 12 months with dozens of foreign oil workers kidnapped. Nine foreigners are currently being held by two different groups.
