Yenagoa - Pirates have launched a spate of attacks in the creeks of the oil-producing Niger Delta region since last Thursday, killing three policemen and abducting at least nine people, security officials said.
Most of those kidnapped were local workers in Africa's biggest oil industry, where piracy in the surrounding waterways and seas is on the rise again after a brief lull, bucking a global trend that has seen pirate attacks fall elsewhere.
In the most recent attack, gunmen on a boat opened fire on police escorting a barge operated by Italian oil company ENI along the Santa Barbara River, killing three policeman.
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"Sea pirates attacked and killed three of our men. They were escorting an Agip (ENI) barge when they were attacked. We have recovered their bodies and the gunboat," police commissioner for Bayelsa state Valentine Ntomchukwu said by telephone.
A security source said the boat's driver had also been kidnapped. ENI officials were not immediately available for comment.
Earlier on Friday, unknown gunmen attacked a boat and abducted six personnel from a local oil services company in the Nembe local government area. On Thursday, around seven pirates on a speedboat boarded a supply vessel, kidnapping the ship's master and its chief engineer.
Piracy and kidnapping are expected to increase further as Nigeria prepares for an election next February, intelligence experts say. This is because elections increase the demand for funding, which some politicians obtain through their links with criminal networks.
Security in the Niger Delta is generally better than it was in the last decade, when the oil industry saw near daily militant attacks on oil installations and frequent kidnapping of oil workers, owing to a 2009 amnesty with militants.
But piracy and oil theft remain a major security headache.