The African Continental Free Trade Area Treaty would remove trade barriers and eventually allow free movement, creating a common market across the continent - much like the European Union.

But Nigerian labour unions have complained that it was bad for the economy and would lead to job losses.

Nigeria, along with South Africa and Angola, has one of the continent's largest economies, the World Bank says. It also has the biggest population.

President Muhammadu Buhari's decision to pull out at the last minute is a setback for the pan-African trade treaty.

A statement said he had cancelled his trip to Rwanda to allow for consultations within Nigeria.

With elections less than a year away, our Africa Editor Will Ross says that the government will want to avoid a row with Nigeria's labour unions and some business leaders who say the African Continental Free Trade Area Treaty will lead to job losses.

The treaty will liberalise trade in goods and services and aims to end the reliance on the export of unrefined minerals.

Source: BBC