Nigerians go to the polls on 25 February, with Mr Tinubu standing as the presidential candidate for the governor APC party.

Speaking to a crowd on the campaign trail in Ogun state on Wednesday, Mr Tinubu said that a fuel shortage in the country as well as moves by authorities to ban old naira notes as legal tender, in favour of newly designed notes, at the end of the month were covert attempts to stop him from becoming president.

President Muhammadu Buhari says the introduction of new notes will help to tackle corruption, counterfeit money and the illicit hoarding of cash.

Mr Tinubu then accused authorities of "hiding" the fuel and the naira notes, but said his supporters would still vote and so he would win.

However, people are questioning what a change in the naira design has to do with Mr Tinubu winning the presidency.

In previous Nigerian elections there have been cases of politicians paying people to vote for them.

"This is quite major," broadcaster Ayo Mairo-Ese said on Arise News. "How does the redesigning of the naira or the unavailability of the naira affect his particular campaign, or the presidential election?" Ms Mairo-Ese asked.

"We have 18 presidential hopefuls. Why is it only the APC presidential candidate that is worried about the redesigning of the naira and saying that it is an act to sabotage his campaign? That's a question that he must answer."

Mr Tinubu has always denied allegations of corruption and vote-buying made against him and says those accusing him of wrongdoing are just jealous of his wealth and success.

He has been a longstanding figure in Nigerian politics for decades and assisted in President Buhari winning office.