Nigerian President Mohammadu Buhari arrives with his wife Aisha, before taking oath of office at the Eagles Square in Abuja, on May 29, 2015
Lagos (AFP) - When Nigeria's new first lady Aisha Buhari appeared at her husband's inauguration wearing what looked like a $50,000 Cartier watch, scores took to the Internet to voice their surprise.
Was it a gift or did she pay for it herself? Hadn't President Muhammadu Buhari been elected for his frugal, clean image and promise to clean up Nigeria's dirty politics?
Others were indifferent, countering that $50,000 was peanuts compared to the billions squandered every year by government mismanagement or simply stolen through rampant corruption.
"The question really is the scale of the greed, not the fact of corruption, which is everywhere," Adewale Maja-Pearce, a Lagos-based writer, told AFP.
The money lost to corruption is mind-boggling in a country where the majority of the country's 173 million people live on less than $2 a day, particularly in the notoriously murky oil sector.
In September 2011, Bukola Saraki, who is now Senate leader, publicly exposed what he called "wastage, lack of transparency, corruption and malpractice" in the fuel subsidy programme.
- Money for empty vessels -
Nigeria is one of the world's biggest producers of crude but a lack of working refineries means oil has to be exported and then its products imported at international market prices.
To keep prices low for consumers, the government sells fuel on the streets at subsidised prices and makes up for the high amounts spent by importers by paying them the difference.
The system is wide open to fraud: some importers rent empty vessels, pay officials to say they have fuel on board and pocket the subsidies.
"They also bring vessels filled with petrol, get the papers and then go to neighbouring countries to sell it there, so they have the double benefit of subsidies and sales," says Debo Adeniran, head of the Coalition Against Corrupt Leaders lobby group.
Saraki said that by the end of August 2011, the hundreds of billions of naira spent on fuel subsidies was already 300 percent above what had initially been budgeted for the entire year.
- How many government accounts? -
Buhari believes graft has made Nigeria a global laughing stock but even he has admitted the scale of the problem is unknown in a country that last year ranked 136th out of 175 in Transparency International's Corruption Perceptions Index.
"In Nigeria now the (state-run) NNPC (Nigerian National Petroleum Corporation), Ministry of Finance, FIRS (Federal Inland Revenue Service)... they do not know how many accounts the government has," he told AFP in an interview this month.
One of Buhari's biggest challenges will be to change mindsets, with Nigeria a country where money talks, particularly when it comes to politics, power and influence.
"Will he have the political will to actually deal with the people who are in the same party who contributed to getting him elected?" asked Idayat Hassan, from Nigeria's Centre for Democracy and Development (CDD).
As if to answer the question, Buhari has yet to appoint a cabinet three weeks after coming to power.
Buhari said government departments were being audited to try to establish what state they were left in by the previous administration.
"I want to get ministers after at least I have seen this report, so that I don't have to appoint a minister today and sack him next week," Buhari added.
- What about Buhari? -
Who will get the sought-after petroleum portfolio is a source of constant, eager speculation, with claims Buhari himself may even take charge of the sector to root out corrupt practices.
The NNPC was at the centre of a row with the Central Bank of Nigeria last year when Governor Lamido Sanusi said $20 billion (18 billion euros) in oil revenue it was owed had gone missing.
President Goodluck Jonathan, who disputed the amount, then sacked Sanusi.
With Buhari -- a former military ruler known for his no-nonsense approach to corruption and "indiscipline" -- awareness of the need to tackle graft is arguably at an all-time high.
The CDD has even set up a website -- the "Buharimeter" -- to monitor whether he fulfils his election promises.
So far, Buhari has only started to address one of them -- to publicly declare his assets. But they have yet to be made public, even though he has submitted them to the Code of Conduct Bureau.
For Maja-Pearce, hope rests in Nigeria's Internet-savvy youth.
"They know what's happening and how much their country is failing," he said.
"If the country doesn't make space for their talents by providing the necessaries then they will bring the house down."