The most high-profile armed group in Nigeria's oil-rich but volatile Niger Delta says it did not carry out Wednesday's attack on a naval vessel that killed five people. Rebels who have waged an increasingly bold campaign in the region have slashed the country's crude oil output. Gilbert da Costa has more for VOA in this report from Abuja.

Spokesman for Nigerian troops deployed in the Niger Delta to provide security for oil workers and facilities, Lieutenant-Colonel Sagir Musa, told VOA about 30 militants were involved in the attack.

"There was an attack at Olubiri navy house, naval ship. It was a naval location, whereby about 30 militants attacked the location at about 1:00 to 2:00 a.m. and the naval personnel were able to successfully repel the attack. They killed three militants and injured many. It is also feared that one naval personnel died in the process, and one civilian," said Musa.

The attack in Olubiri was the latest in a series of violent acts aimed at derailing oil production in the Delta. Oil companies have seen output dwindle since militants pledged to ramp up attacks in the region.

The Movement for the Emancipation of the Niger Delta, MEND, a major militant group operating in the Niger Delta says it was not behind the attack. No group has claimed responsibility.

The attack coincided with an announcement Wednesday that Britain and Nigeria would set up a security training force to help the West African country deal with insecurity in the southern oil producing region.

Musa says the Nigerian military is stepping up security operations in the Niger Delta.

"We are beefing up our efforts. We are concentrating seriously. We are monitoring. We are supervising our men to ensure we keep up to our responsibility," he said.

President Umaru Yar'Adua made the Niger Delta, with its oil and gas riches, one of his priorities when he came to office a year ago. But it remains as violent and poverty stricken as when he arrived.
 
A Niger Delta community blew up a crude oil pipeline operated by Italian energy company Eni on Thursday, shutting around 20,000 barrels per day.

Militants say that the Delta does not get a fair enough share of the huge revenues it makes for the country.

The production shortfall in Nigeria has contributed to an international spike in oil prices over the last couple of months.