The main militant group in Nigeria's restive southern region said Friday it had sabotaged a major oil pipeline and threatened further attacks in Africa's biggest crude producer.
The Movement for the Emancipation of the Niger Delta said its fighters hit the pipeline operated by a Royal Dutch Shell PLC joint venture in southern Rivers state overnight.
The group gave no other details, but said more violence was to come.
Shell said a pipeline leak appeared to have been caused by explosives. The company said it had isolated the line for repairs and that some crude had leaked. A company spokeswoman said "some small quantity of production" had been shut to allow for repairs.
The militant group's bomb attacks since early 2006 have targeted oil pipelines and other infrastructure, cutting nearly one quarter of Nigeria's normal petroleum output and helping push oil prices to historic highs on international markets.
The militants say they are fighting to force the federal government to send more oil industry revenue to their areas, which remain desperately poor despite decades of oil production.
The group also says it wants the release of one of its leaders, Henry Okah, an alleged illegal arms dealer.
Okah is on trial in a closed court on treason and terrorism charges, which can carry the death penalty. He was extradited to Nigeria earlier this year after his arrest last year in Angola.
The group has continued its campaign of attacks even after the government met earlier demands for the release of other leaders. Militancy and crime are closely intertwined in the southern Niger Delta, with fighters stealing crude oil for illegal resale or robbing banks one day and fighting government forces the next.