Mr Farage told The Telegraph he was "laughing" about the allegations and blamed The Guardian for running the story because "they cannot accept Brexit, they cannot accept Trump".

He added: "I never been to Russia, I have never had any business dealings in Russia. Much of the world I have - but I never did Russian business even when I was in commodities.

"I have no Russian links or connections of any kind at all. And the idea that I can be a 'person of interest' is frankly laughable."

"Persons of interest" are those thought to have information that may help the FBI with their inquiries.

“One of the things the intelligence investigators have been looking at is points of contact and persons involved,” one source told the Guardian.