As oil minister during military rule in the 1970s, Muhammadu Buhari oversaw the birth of the Nigerian National Petroleum Corp.

Now, as democratically elected president, he intends to break up the opaque bureaucracy, which manages the oil assets of Africa’s biggest crude producer, to ensure taxpayers get their fair share. History isn’t on his side.

“No Nigerian leader, including Buhari himself from the 1980s, has managed to sanitize the oil sector,” said Philippe de Pontet, head of the Africa practice at the Eurasia Group in New York. “Buhari’s challenge is not only to depoliticize NNPC but to disentangle its vested interests and its rogue commercial operations, which won’t be easy.”

Buhari made cleaning up the 24,000-employee colossus -- the largest government-owned company -- a key plank in the election campaign that toppled President Goodluck Jonathan in March. He plans to split the NNPC in two, creating a regulator and a vehicle for investments, according to Femi Adesina, a presidential spokesman.

So far the president has fired the board and management of the company and replaced its Jonathan-appointed chief with Emmanuel Ibe Kachikwu, who was executive vice-chariman of Exxon Mobil Africa. He has also ordered a review of oil-swap contracts and barred 113 vessels from loading oil and gas -- about 250,000 barrels of Nigerian crude, about 10 percent of the country’s daily output, are stolen daily, Buhari has said.

‘Mind-Boggling’

“A lot of damage has been done to the integrity of Nigeria with individuals and institutions already compromised,” Buhari told an audience in Washington last month. “The amount involved is mind-boggling.”

Nigeria’s transparency watchdog says the NNPC has diverted more than $30 billion in oil revenue from the state since 2009. That exceeds the annual economic output of more than half the nations in Africa and roughly equals the federal budget.

The situation is increasingly desperate because, with a halving in Brent crude prices in the past year, government coffers are “virually empty,” Buhari said after less than a month in office; about two-thirds of the country’s almost 180 million people live on less than a dollar a day.

Set up to defend Nigeria’s interests with foreign majors, the company controls an aggregate 55 percent share in joint ventures with the likes of Royal Dutch Shell Plc, Exxon Mobil Corp. and Chevron Corp. Crude exports account for about two-thirds of government revenue.

Four Towers

NNPC’s four-tower headquarters building in the capital dominates Abuja’s skyline. It’s the landlord to the petroleum ministry, whose minister chairs the organization. Group managing director Kachikwu is its sixth head in five years.

For all its importance to Nigeria, the NNPC is largely inscrutable. It had the worst disclosure record of 44 energy companies analyzed in a 2011 report by anti-corruption nonprofit organizations Transparency International and the Revenue Watch Institute.

Ohi Alegbe, a spokesman for the NNPC, declined to comment, citing the pending reorganization, when contacted by phone Thursday. The NNPC consistently denies any wrongdoing.

Allegations of missing funds go back as far as when Buhari was oil minister. The Lagos-based Punch newspaper reported in 1978, a year after the NNPC took its current name, that the company failed to remit the equivalent of about $3.5 billion it owed the Treasury.

Military Investigations

In the 1990s, a military-sanctioned investigation found $12 billion in oil revenue was unaccounted for under the government of army ruler Ibrahim Babangida.

After the return to democratic rule in 1999, Nigeria signed up in 2005 to the Extractive Industries Transparency Initiative, a global effort in which governments committed to disclosing all extractive industry payments. Since then, the Nigeria Extractive Industries Transparency Initiative, or NEITI, has said at least $23.2 billion due wasn’t deposited into the national accounts from 2009 to 2011.

More recently, then-central bank Governor Lamido Sanusi alleged in a memo to Jonathan that the corporation retained as much as $50 billion in oil revenue that was due the government.

Sanusi’s claims led Jonathan to commission a PricewaterhouseCooper LLP audit for the period from January 2012 to July 2013. PwC found the NNPC had a “blank check” to spend without control and had accounting and monitoring systems filled with “significant” discrepancies.

The NNPC should refund as much as $4.29 billion to the government, the report said. Then-Petroleum Minister Diezani Alison-Madueke said on April 22 that the company had started to refund the minimum $1.48 billion the audit recommended.

Opaque Debts

Then, there’s the money it owes commercial partners.

The NNPC’s debts to its eight joint ventures have “ballooned over the years,” according to a ruling All Progressives Congress policy report submitted to Buhari after the election and obtained by Bloomberg.

In 2012, the state company paid $6.9 billion of the $10.4 billion it owed. The difference was covered by loans from international oil companies including Shell, Exxon Mobil and Total. The companies declined to comment.

Critics say any shakeup would have to resolve NNPC’s dual role as regulator and oil company.

Corruption would vanish if Buhari refocused the NNPC as just a regulator “so people like us can get on with the job,” said Kola Karim, head of a Nigerian oil explorer.

Producing about 60,000 barrels a day, Karim’s Shoreline Group, founded in 1997, could be pumping more than double that amount if the NNPC wasn’t a partner in his business and with civil servants slowing investment decisions, he said.

Senior officials in Buhari’s party are calling for even more drastic measures.

“We should replace the NNPC,” Nasir el-Rufai, the governor of northern Kaduna state, said in Abuja this month. Nigeria needs to “tackle the monster that the NNPC has become.”