Italian oil major Eni said on Sunday there has been an oil spill on its Nembe-Obama pipeline in Nigeria's onshore Niger Delta due to sabotage.
"Repair work has started. The wells of Nembe South have been closed with minimal impact on production," a spokesman for the company said.
In 2009, Eni said its net output in Africa's biggest oil producer was 128,000 barrels per day (bpd).
Sabotage of foreign oil company's infrastructure in the Niger Delta has reduced since an amnesty for militants in 2009, but there has been a surge in oil theft in the region this year.
Oil companies and the Nigerian government have accused communities of causing spills to claim compensation for the environmental damage caused.
Locals often say oil companies are slow to react to spills and do not clean them up properly.
"It is indeed sad and most unfortunate that in spite of the huge consequences occasioned by the oil spill, Eni has failed to discuss development," Nengi James, chairman of an oil community committee in the Nembe region, said.
"They (oil firms) allow oil spills to spread to rivers and mangrove forests before coming for inspection and clean-up."
The environmental damage caused by oil spills in the Niger Delta has destroyed fishing livelihoods and means some communities drink water containing deadly levels of toxins, the United Nations said in a report last year.
Foreign oil majors, the Nigerian government and Niger Deltans blame each other for the damage done. Shell, the largest producer in Nigeria, estimates 150,000 bpd of crude oil is being stolen.