The move is aimed at making the trade more lucrative as Nigeria is losing out by not producing much shea butter locally. The country produces nearly 40% of the world's annual crop, but it only accounts for 1% of the $6.5bn (£4.8bn) global market - a situation Vice-President Kashim Shettima described as "unacceptable".

Harvested fruit from shea nut trees have to be crushed, roasted and boiled to extract their oil to produce the shea butter used in cosmetics. The butter is also used in the food industry in the production of some sweets like chocolate and ice creams - and in pharmaceuticals too. Shea trees grow in the wild from West to East Africa - a vast strip known as the "shea belt". Small-scale farmers, often women, also plant and harvest them in these areas.

Shettima said the temporary ban would enable Nigeria to move from being an exporter of the raw nuts to a global supplier of refined shea products. ''It is about industrialisation, rural transformation, gender empowerment and expanding Nigeria's global trade footprint," the vice-president said during the announcement at State House in the capital, Abuja. The short-term aim, he said, was to see Nigeria's earnings from the fruit of the shea nut trees grow from $65m to $300m annually.

Nigeria Agriculture Minister Abubakar Kyari has said the West African nation produces a crop of 350,000 tonnes a year - with nearly 25% of that disappearing over the borders in unregulated informal trade. According to agriculture expert Dr Ahmed Ismail, much of the harvest comes from villages in central Nigeria. ''A lot of poor people who grow the crop and rely on it for sustenance are struggling to get by because of a lack of regulation, which means they get so little despite its high value internationally," the academic from the Federal University of Minna told the BBC. (BBC/ AFP/Getty Images)