It was alleged that the company had failed to remit 20 billion US dollars owed to the state.
President Goodluck Jonathan ordered an audit of the national energy company in early 2014 after former central bank governor Lamido Sanusi said an estimated 20 billion US dollars in oil revenue had been withheld from the Federation Account.
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NNPC added that the audit said 1.48 billion US dollars should be sent to the government by the corporation's upstream subsidiary, the Nigerian Petroleum Development Company (NPDC) but that this amount was not part of the missing crude revenues.
It said the delay in the NPDC remittance was due to the reconciliation processes between the Department of Petroleum Resources (DPR) and the NNPC.