A Niger Delta rebel group fighting what it calls government and foreign exploitation has claimed it attacked a Shell-operated oil pipeline, ending a two-month truce.
Nigeria's main rebel group Saturday said it attacked an oil pipeline operated by Shell and Chevron, ending a two-month truce, and accused the government of using the president's ill-health to stall peace talks.
The Movement for the Emancipation of the Niger Delta (MEND) claimed the attack in an e-mail statement, like its previous strikes, and located the pipeline in Abonemma, some 50 kilometres (30 miles) west of Port Harcourt, the country's oil hub.
The "warning strike (was) carried out by five boats involving thirty five fighters armed with assault rifles, rocket launchers and heavy calibre machine guns ... on a major Shell/Chevron crude pipeline in southern Rivers State," MEND said.
A Shell official said the company was not aware of any attack on its facility.
Earlier a spokesman had told AFP "we are still investigating the report".
MEND had on October 25 announced an indefinite ceasefire in response to a government amnesty programme for militants in the restive oil region to lay down their arms.
The group also named a team to negotiate with the government on how to end the unrest.
MEND said it would now review the ceasefire within 30 days, blaming the government for suspending ongoing peace talks because of the ill-health of President Umaru Yar'Adua, hospitalised since November 23 in Saudi Arabia.
It is not yet clear when Yar'Adua - said to be suffering from acute pericarditis, an inflammation of the membrane covering the heart - will return to Nigeria and official information on his health has been limited.
His latest trip was the third to the Saudi Arabian port city in four months, all believed to have involved hospital visits.
Apart from announcing this week the creation of five committees that will address oil, environmental and disarmament issues following the amnesty process in the Niger Delta, further talks on the crisis in the region have stalled since Yar'Adua's hospitalisation.
"While the Nigerian government has conveniently tied the advancement of talks on the demands of this group to a sick president, it has not tied the repair of pipelines, exploitation of oil and gas as well as the deployment and re-tooling of troops in the region to the president's ill health," MEND said.
"While wishing the president a speedy recovery, a situation where the future of the Niger Delta is tied to the health and well being of one man is unacceptable," it said.
MEND vowed to continue "its fight for the restoration of the land and rights of the people of the Niger Delta which has been stolen for 50 years."
The Niger Delta has for more than three years been a haven for armed militants claiming to be fighting for a greater share of oil wealth for their communities.
At the peak of the unrest Nigeria, the world's eighth largest exporter of crude, saw its output slashed by a third.
Following the amnesty deal which ended last month, Nigeria's oil output has risen to around 1.98 million barrels per day, according to latest report from the International Energy Agency.