Nairobi/Abuja - A Nigerian militant group claimed Wednesday 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.

The claims could not immediately be verified, although the Nigerian military normally issues a counterclaim very different from the militants.

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

The group claims to have attacked and seriously damaged a Chevron platform, another Shell flow station and an oil pipeline over the last few days.

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

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. (dpa)