Nigeria’s state oil company failed to remit 4.9 trillion naira ($25 billion) to the public purse between January 2011 and December 2015, the Revenue Mobilization Allocation and Fiscal Commission (RMAFC) said on Tuesday.

It is the latest announcement on the issue of remittance by the Nigerian National Petroleum Corporation (NNPC) in recent days. Last Monday the auditor-general said 3.2 trillion naira was not remitted in 2014, which NNPC later denied.

President Muhammadu Buhari took office in Nigeria last May, saying he would end corruption and mismanagement.

“Records at the Commission’s disposal indicate that between January 2011 and December 2015, the total indebtedness of NNPC to the Federation Account was 4.9 trillion naira,” said RMAFC, an independent body, in a statement.

Constitutionally, NNPC must hand over its oil revenue – which makes up about 70 percent of national income – and money is then paid back based on a budget approved by parliament. But the act establishing the state oil company allows it to cover costs before remitting funds to the government.

RMAFC said its figure for the money that had not been remitted “included NNPC’s claims for subsidy on petroleum products, crude and product losses, strategic reserves and the pipeline maintenance cost”.