Lagos - where rich and poor live side by side
Nigeria is Africa's largest economy and the continent's biggest oil producer.

But it is a country where more than half the population lives in poverty, and 60% of the urban population cannot afford the cheapest house.

There are also some very rich Nigerians indeed and the gap between rich and poor is all too clear to see in the country's largest cities.

Competing claims
The government argues that it has combated poverty and blames past governments for mismanaging the oil industry and the economy.

"It is not that poverty has reduced considerably, no. I am saying that what has happened now is that we are dealing with the issue of poverty," said vice-president Prof Yemi Osinbajo.

Mr Buhari's principal opponent in the election, Atiku Abubakar, says Nigeria's economy has never been in a worse state than it is now.

"The most important question in this election is: are you better off than you were four years ago, are you richer or poorer?"

The Nigerian economy has only recently shown signs of recovery after a period of recession that ended in 2017.

The unemployment rate provided by the government's National Bureau of Statistics is more than 20%.

Here's another key statistic - about 60% of the population lives in absolute poverty - measured by the number who can afford only the bare essentials of shelter, food and clothing.

Experts see little sign that the situation for the poorest has improved significantly.

"With increase in population and continuing lack of jobs, it is evident that the gulf between the haves and the have nots will continue to widen in the future," said Dr Bongo Adi, an economist at the Lagos Business School.

There's certainly a widespread perception that inequality is getting worse.

"Nigeria has a long history of mismanagement, corruption and disregard for due process" that has contributed to the high number of people living in poverty, says Abdulazeez Musa, Oxfam's Nigeria-based analyst.

As for the gap between rich and poor, Nigerian economist Bismarck Rewane estimates that only 5% of the population controls roughly about 40% of Nigeria's wealth.

Poverty-reduction policies do exist, he says, but they are not backed up by the political will or the good governance to implement them.

"Vested interest is far in excess of national interest," he says.

Poverty rates are higher in northern states than they are in parts of the south.

Sokoto State in the far north-west of the country has the highest level of poverty at 81 % while the figure for the south-western state of Lagos is 34%.


Housing as a measure of poverty
About half of Nigeria's population lives in cities, but the divide between the poor and the rich has created a paradox - many newly-built houses in the wealthier areas of Lagos are empty, while overcrowding is a major issue in many poorer areas.

The UN estimates that 69% of urban residents in the country live in slum conditions, with the housing shortfall of close to 18 million units.

Building or buying a house is expensive. To construct a three-bedroom house costs $50,000 (£38,500) compared with $36,000 in South Africa and $26,000 in India, according to the World Bank.

The Centre for Affordable Housing Finance in Africa says a standard three bedroom, middle-income apartment in urban locations in Nigeria currently costs $5,000 a year to rent or $100,000 to buy.

Only about 40% of urban households can afford the cheapest newly-built house ($16,351).


Poverty or inequality?

Although there is a general recognition that Nigeria is highly unequal, it is hard to quantify inequality because of the lack of up-to-date data, says economist Dr Zuhumnan Dapel.

But there is a wider point about the study of inequality, he says. Those in developing economies care less about income inequality than they do about living in poverty.

"Whether their people are living below the poverty line., the main aim is getting people out of poverty," he says.

And this is where Nigeria faces its greatest challenge.

According to the World Bank, Nigeria is now the country with the most poor people in the world, overtaking India.

The Bank is is cautious over the reliability of the data, but it does suggest the immense scale of the problem the country is facing - whoever wins the forthcoming elections