Abuja - A Nigerian militant group Wednesday claimed it had destroyed a Shell oil flow station in the oil-rich Niger Delta as a wave of attacks against oil installations entered its fourth day.

Jomo Gbomo, a spokesman for the Movement for the Emancipation of the Niger Delta (MEND), said it had destroyed Shell's Orubiri flow station in Rivers State in a joint attack with the Niger Delta Volunteer Force (NDVF).

Gbomo said that all of the soldiers guarding the facility were killed.

A spokesman for the Nigerian military in the Delta, however, said that none of the navy personnel on duty at the facility was killed.

"They (MEND) came in eight speedboats, detonated dynamite, bombs and lobbed hand grenades at the facility," Lieutenant Colonel Sagir Musa, told Deutsche Presse-Agentur dpa.

"The facility caught fire due to ... massive dynamite and bomb explosions," he added.

Shell spokesman in the region, Precious Okolobo, also confirmed the attack and said that damage had been suffered to another company pipeline at Rumueke, also in Rivers State.

Gbomo said MEND had attacked the major crude oil pipeline, which belongs to both Shell and Italian oil giant Agip, at Rumueke.

Militant groups such as MEND often attack oil installations and kidnap expatriate workers, saying they are fighting for a greater share of profits from oil exploitation for the poor of the region.

The government says they are merely criminal gangs intent on stealing oil and extorting money.

The unrest has cut oil production by around a fifth since early 2006, helping to push up global oil prices and allowing Angola to surpass Nigeria as Africa's biggest oil exporter.

Okolobo would not reveal by how much Shell's production would be cut as a result of the latest string of attacks.

"Shell is taking stock and we shall make our position known soon," he said.

MEND on Sunday declared an "oil war" after Nigerian military forces attacked militant positions with gunboats and helicopters.

The group has warned oil workers to leave the region and said oil tankers should not attempt to dock. (dpa)