Nigeria's main militant group says it bombed two oil pipelines in the restive southern Niger Delta as part of its campaign against the oil industry.
The Movement for the Emancipation of the Niger Delta, MEND, said its fighters attacked two major pipelines belonging to Royal Dutch Shell and the Italian group Agip.
The rebel group said in a statement it destroyed the pipelines in predawn attacks in Bayelsa state. There was no immediate comment from Agip, but Shell officials said they were investigating the report.
A spokesman for the Nigerian military in the Niger Delta, Colonel Rabe Abubakar, told VOA that security forces will crush any further threat to the oil industry.
"I am telling you that these guys who are committing these sabotage activities are in the communities. We are 100 percent on top of the situation and we will keep on doing our best in this region in getting rid of these criminals, criminality, especially militancy," he said. "And those who are carrying out the sabotage their days are numbered, and in a very short distance the story will change. I am assuring you this."
Nigeria is Africa's biggest oil producer. But attacks in the Niger Delta, which accounts for almost all of Nigeria's oil output, have cut more than 20 percent of the country's crude exports since early 2006.
The head of the Nigerian Petroleum Corporation was quoted by a local newspaper as saying the violence has forced oil companies to hold about 600,000 barrels of crude a day in the past two months.
Hopes that a government amnesty offer a few weeks ago could lead to a period of calm in the troubled Niger Delta are being shattered by MEND's widening campaign of sabotage. Analysts fear the government's latest attempt to bring peace to the oil-rich region is now in danger of falling apart.
MEND claims to be fighting for a greater share of the oil wealth in the Niger Delta, a vast network of mangrove swamps where villages are trapped in poverty, despite five decades of oil exploitation.