International Monetary Fund chief Christine Lagarde said on Tuesday she was not in Nigeria to negotiate a loan and urged Africa's biggest economy to diversify its revenue to try and get out of an economic crisis fuelled by the fall in oil prices.

Lagarde was speaking at the presidential villa in the capital Abuja moments after holding talks with President Muhammadu Buhari.

She backed Buhari's fight against corruption terming it "very important" and said the president's reform push could have a positive impact in the region.