Armed militants killed a Nigerian and kidnapped six foreign oil workers in an attack on an oil industry vessel off Nigeria's coast yesterday, security sources and the Italian government said.

Italy's Foreign Ministry said four of the hostages were Italians. Security sources said one of the others kidnapped was believed to be American, while the nationality of the sixth person could not be immediately established.

"The militants shot one navy personnel and compelled the crew to throw a rope down to give them access by using dynamite," one security source said.

Industry sources said the vessel, called Oloibiri after Nigeria's first oil well, is operated by US energy giant Chevron.

The overnight attack forced Chevron to shut down output at a small offshore oilfield.

"We have shut down 15,000 barrels per day from the Funiwa oilfield," a company spokesman said in London.

Nigeria's oil output has been reduced by 500,000 barrels per day, or a fifth of production capacity, since a series of raids on Royal Dutch Shell oilfields in February last year forced their closure.

In a separate incident, unidentified gunmen abducted the mother of Rivers state governor-elect Celestine Omeiha from her village near Africa's oil heartland of Port Harcourt.

"We have not yet established contact with the kidnappers so we don't know the reason why they took her," Rivers state police commissioner Felix Ogbaudu said.

The abduction is apparently a fall-out from the April 14 state elections - which monitors said were marred by fraud - because Niger Delta militants rarely kidnap Nigerians.

In the Niger delta, an increasing number of armed groups demanding jobs, benefits or control of oil revenues have attacked industry facilities, kidnapped expatriate staff and fought with security forces.

But the lines between militancy and crime are blurred in the delta, a vast wetlands in southern Nigeria that accounts for all oil production from the world's eighth biggest exporter.

(Xinhua News Agency May 2, 2007)