One in three Africans - 313 million people - are now defined as middle class, according to the African Development Bank, which has been studying the income of people across the continent. Photographer Philippe Sibelly has been documenting Africa's middle classes for his project The Other Africa, intended to show there is more on the continent than poverty and conflict. Antoine is a tennis instructor in Gabon's capital, Libreville.

The bank says the African middle classes - someone living on between $2 and $20 a day - usually have salaried jobs or own small businesses, and are the engine driving future economic growth and development. Manal is a successful singer and TV presenter in Algeria's capital, Algiers.

Firms from around the world want them as customers and plan to sell them everything from motorcycles to modems, the bank says. Mohamed works in a mobile phone shop in Nouakchott, the capital of Mauritania. He says you can get a signal "deep in the Sahara Desert".

In Ghana, vehicle ownership has increased by 81% since 2006. Samuel and Bright are waiters in a Chinese restaurant in Osu, a suburb of Accra - a sign of the massive investment by Chinese companies in African countries.

The bank says members of the middle classes are having fewer children, are better educated and more geographically concentrated in urban areas or along the coasts. Mustapha, a painter, and his wife Nouria, a civil servant, live in the Algerian capital, Algiers.

Tunisia, Gabon and Botswana have the largest middle classes, while Liberia, Mozambique and Rwanda have the smallest. Marie Georgina is a salesperson in a fashion boutique in Libreville, Gabon.

The richest people in Africa remain in the north, although there has also been a rise in income for many people in the sub-Saharan region over the past 30 years. Amilcar is a pilot for the national airline of Cape Verde, whose tourism industry is thriving as more people have the money to fly.

The bank’s chief economist says that while there were several reasons behind the growth of the middle classes, education has been the main catalyst. Aretha Louise is a radio presenter and producer at CRTV, Cameroon’s national broadcaster. She says there has been a new demand for information and media.

The report says a characteristic of the middle class is to seek better health care. Francois Xavier is an optician in Dakar, Senegal, where glasses cost a fraction of what they would in Western countries.

Good governance has also played an important role, because it allows businesses to flourish and wealth accumulation to take place. DJ Paco, also known as Papis, is a DJ and rap artist in Nouakchott, Mauritania, one of the countries which migrants pass through as they try to reach the West. He advises young people to stay at home. "The amount of money needed to leave for Europe would get you a nice little business here."

The bank warns, however, that 60% of those defined as middle class - those spending between $2 and $4 a day - are vulnerable to economic or political shocks, and could easily fall back below the poverty line. Yao works in a large supermarket in the centre of Lome, Togo.