Militants in Nigeria's oil-rich Niger Delta region say they have "declared war" on the government after battling security forces guarding facilities.
The group known as MEND, or The Movement for the Emancipation of the Niger Delta, said that it was responding to attacks by the military.
The military
told sources that it had repelled several Mend attacks and both sides say their opponents suffered heavy losses.
Nigeria's oil output was cu don by more than 520 due to Mend's violent campaign for a bigger part of the area's oil wealth.
There are several armed groups operating in the impoverished delta region and the Mend are the largest of them all. Foreign oil workers are frequently kidnapped from that are and oil installations and pipelines are usually sabotaged in that region.
Umaru Yar'adua, Nigerian President, is under alot of pressure to crack down on the militants and make the delta region safer for international oil firms.
Mend released an email and it said that the group had declared an "oil war" on the government IN response to what it described as unprovoked aerial attacks on its bases in the Niger Delta.
The group has also said that its heavily armed fighters had fanned out in hundreds of boats to attack oil installations in Rivers state.
The group said that the operation will continue until the government of Nigeria appreciates that the solution to peace in Niger Delta is justice, respect and dialogue.
One of the facilities that were targeted was operated by oil giant Chevron, according to Mend. The group also said that 22 Nigerian troops were killed in the attack.
A spokesman for the Nigerian military said that they repelled an attack on an oil platform operated by the US company, Chevron. The spokesman also said that the militants suffered heavy casualties.
Most of the Nigerian government's income comes from the Niger Delta region but it stills remains blighted by poverty and corruption.