The Chatham House on Tuesday said Bola Tinubu ambushed its chairman when he appeared for an interactive session on Monday morning.
The frontline British think-tank said the ruling All Progressives Congress presidential candidate undermined its normal arrangement and did not seek prior permission to act in the manner he did.
Mr Tinubu, catheter device to take his bodily waste and speaking gibberish during public appearances.
The presidential candidate has dismissed public concerns about his health, saying it was misplaced since he only needs his mental capacity to govern and not his physical capacity, which should be reserved for manual labour workers.
