Italian energy group Eni said on Thursday its Ogboinbiri gas pipeline in Bayelsa state had been vandalised, causing a leak and production losses.
A spokesperson for Eni said "third parties" had cut the pipeline with hacksaw.
"The line is depressurized and is currently being repaired. Production losses due to the shutdown are important," the spokesperson said.
Oil and gas output in Nigeria have fallen due to theft and vandalism of pipelines, leaving gas producer Nigeria LNG Ltd's terminal at Bonny Island operating at 60% capacity.
Eni, along with state-oil company NNPC Ltd, Shell and TotalEnergies own shares in Nigeria LNG.