The agency said the two letters were forgeries.

The first letter surfaced on Twitter in late January and is a purported reply to an enquiry to the agency on the alleged activities of Mr Tinubu.

https://twitter.com/lanreisrael/status/1617909684656287744

It was viewed hundreds of thousands of times by Twitter users in the country.

The NCA told the BBC that it had denied the letter when it was drawn to their attention.

The second letter appeared to “challenge” the first letter.

It suggested that the NCA was threatening to take legal action against a rival presidential campaign team, which it claimed, forged the first letter.

https://twitter.com/AKOBI22/status/1620747206616813571

The NCA has confirmed to the BBC that the second letter did not come from them.

The NCA is a law enforcement agency in the UK that focuses on local and international cybercrime, human trafficking, drug trafficking, organised crime, economic crime and weapons trafficking.

A recent investigation by the BBC disinformation unit found that political parties and campaigns in Nigeria were using social media influencers to spread disinformation to discredit their political rivals.

Nigerians will go to the polls on 25 February to elect a new president.