Oil major Shell's Nigerian subsidiary is investigating reports that an illegal oil tap ran for nine years on a pipeline it operates, a spokesperson said on Wednesday.

An NNPC spokesman said on Sunday the theft point extended from the Trans Escravos pipeline and that the Afremo platform, operated by the Shell Petroleum Development Company of Nigeria (SPDC), was the suspected exit point of the stolen crude.

"We are also conducting an investigation to establish where the theft lines end and whether there have been any breaches of the unmanned platform's security barriers (locks etc.) or any unauthorised use of the equipment on it," an SPDC spokesperson said in an email.

SPDC said it had detected illegal connections as part of regular surveillance and would launch a joint investigation with regulators to "establish the nature and condition" of the lines before removing them.

NNPC pointed to the theft line discovery as evidence that Nigeria's coordinated interventions, including contracts with companies owned by former militants, to crack down on theft were paying off.

Large-scale theft from Nigeria's pipelines has throttled exports, forced some companies to shut in production and crippled the country's finances.

Reuters