Royal Dutch Shell suffered another major setback in Nigeria, Africa's top oil producer, as four workers were abducted and a pipeline demolished in the country's restive oil-producing region in the south.

Company spokesmen said it had been force to cut production of some 226,000 barrels of oil as a result of the incidents, as world oil prices climbed a dollar to a three-month high on Thursday.

The kidnapping occurred on Wednesday afternoon when armed men, riding in three boats, stormed a vessel servicing a Shell-operated oil field offshore Nigeria's southern coast, forcing it to shut the 120,000 barrels of oil per day platform.

"We can confirm that four persons were abducted from a support vessel in SNEPCO (Shell's subsidiary in Nigeria) operated EA shallow offshore field by armed men who arrived in three boats at about 15:55 (GMT 14:55) yesterday," a Shell spokesman told Xinhua.

"No fatalities were reported during the incident although one of the abducted persons sustained injuries. No grievances or demands have so far been made to SNEPCO or the service companies," said the spokesman.

Non-essential service personnel on the field's floating production storage and offloading vessel, the Sea Eagle, which is moored some 16 km offshore in water depths of about 25 meters, have been evacuated in line with emergency response procedures, he said.

And on Thursday evening, the spokesman said the whereabouts of workers, a Honduran, a Bulgarian, a Briton and an American, remained unknown. "We are yet to find them, the authorities are working on the case," he said.

Also on Wednesday, a pipeline operated by Shell in southern Nigeria was attacked by unidentified persons and currently the company was making efforts to repair it, another Shell spokesman told Xinhua.

"The pipeline in Bayelsa state was vandalized on Wednesday by unknown persons but it's not an explosion. Some 106,000 barrels of oil were affected," said the spokesman.

The incidents came a week after Shell lifted the suspension of crude oil export from the west African country following a pipeline explosion that had initially cut production by 180,000 barrels per day in December.

Nigeria is the biggest oil producer in Africa with a daily output of 2.5 million barrels, while Shell accounts for half of the country's oil production, but the situation in the country's oil regions in the south is turbulent.

Local villagers frequently shut off oil wells, kidnap oil workers or commit other forms of violence to blackmail companies operating in the oil fields as they accuse the oil firms of not doing anything to develop the impoverished area.

(Xinhua News Agency January 13, 2006)