Abuja  - Royal Dutch Shell said Thursday it has shut down production at its main offshore oil field in Nigeria after a militant attack.

"I can confirm that the Bonga field in western Niger Delta was attacked early today," Shell spokesman Precious Okolobo said. "Production at the facility has been shut off, but we cannot confirm further details at the moment."

Militant attacks have cut production in Nigeria by almost a quarter since the beginning of the year, contributing to sky- rocketing global oil prices.

The closing of the Bonga field, which can produce 225,000 barrels per day, cuts the West African nation's capacity by 10 per cent.

Army Lieutenant-Colonel Sagir Musa, spokesman of the troops responsible for providing security to oil-production facilities, confirmed the attack but said the situation had been brought under control.

Militants in the impoverished Niger Delta regularly attack oil production facilities and abduct oil workers as they press for a bigger say in oil exploitation in the area.

Nigeria is second only to Angola in oil production in Africa. In spite of its oil wealth, the majority of Nigerians live below one dollar a day. (dpa)