Nigeria's state-run oil firm withheld some 3.2 trillion naira ($16.2 billion, 14.6 billion euros) from the sale of crude oil in 2014, according to a government report from auditor-general Samuel Ukura.
"From the examination of NNPC [Nigerian National Petroleum Corporation] mandates to [the] CBN [Central Bank of Nigeria] on Domestic Crude Oil sales... [the] amount not remitted to FACC [Federation Account Allocation Committee] was N3,234,577,666,791.35," the report read.
A total of $235.7 million made from gas sales was also not paid to the federal government but "transferred to some undisclosed Escrow Accounts," said the audit, which was presented to parliament on Monday.
Non-remittance of crude oil revenue from the NNPC caused a scandal in February 2014 when the former CBN governor Lamido Sanusi said $20 billion had not been sent to the bank from January 2012 to mid-2013.
Sanusi was suspended just months away from leaving office in what was seen as a political move by then-President Goodluck Jonathan to silence an arch critic and cover up endemic fraud.
Jonathan and his government disputed the figure.
The NNPC has long been seen as corrupt and opaque but President Muhammadu Buhari has embarked on a clean-up campaign, sacking the entire board and calling for greater transparency.
Buhari, elected last year on an anti-corruption ticket, has said "mind-boggling" sums of public money have been stolen by crooked officials in previous administrations.
Nigeria, which is Africa's leading oil producer, is struggling from the fall in revenue caused by the global slump in oil prices since mid-2014, stunting growth, weakening the naira and driving up prices.