Nigeria's President Muhammadu Buhari on Sunday denied claims that he had died and been replaced by a Sudanese impostor or a clone, breaking his silence on a rumour that has circulated on social media for months.

Mr Buhari, who is running for re-election in February, spent five months in Britain last year being treated for an undisclosed illness. One theory widely aired on social media - and by some political opponents - was that he had been replaced by a lookalike from Sudan called Jubril.

No evidence has been presented, but videos making the claim have still been viewed thousands of times on YouTube and Facebook.