London: Britain's Nigel Farage, a leading Brexit campaigner, has branded as "hysterical" a new report stating he is a "person of interest" in the US investigation into possible collusion between Russia and Donald Trump's presidential campaign.

The Guardian newspaper said on Thursday that Farage had not been accused of wrongdoing and was not a suspect or target of the US investigation. 

But it said the former leader of the United Kingdom Independence Party (UKIP) had "raised the interest" of FBI investigators because of his relationships with individuals connected to both the Trump campaign and Wikileaks founder Julian Assange. The report stated being a person of interest meant "investigators believe he may have information about the acts that are under investigation and he may therefore be subject to their scrutiny."

Mr Farage met Mr Assange in March this year at the Ecuadorean embassy in London where he has been holed up for five years.

Responding to the Guardian report, Mr Farage told The Daily Mail on Thursday: "I don't believe it, I have no connections. I have never been to Russia. I have never had any business dealings with Russia."

Taking to Twitter, Mr Farage branded the story "hysterical" and "fake news".

"In response to the Guardian article, it has taken me a long time to finish reading because I am laughing so much at this fake news," he said.

"This hysterical attempt to associate me with the Putin regime is a result of the liberal elite being unable to accept Brexit and Trump.

"I consider it extremely doubtful that I could be a person of interest to the FBI as I have no connections to Russia."

When asked about the Guardian report, a UKIP spokesman said it was absurd.

"To my knowledge, the only serious Russian politician that Nigel has spent time with is Garry Kasparov," the spokesman said.

Mr Kasparov, a democracy activist, is a chess grandmaster who was the former world chess champion.

CIA Director Mike Pompeo has accused Assange's Wikileaks of seeking to interfere in the US election when it distributed material hacked from Democratic National Committee computers during the 2016 campaign.

Mr Pompeo said Russia's GRU military intelligence service had used Wikileaks to distribute the material and concluded that Russia stole the emails and took other actions to tilt the election in favour of Mr Trump, a Republican, over Democratic candidate Hillary Clinton.

Mr Farage, who has campaigned for decades for Britain to leave the European Union, was a vocal backer of Trump. He met Trump in New York just days after the election and attended the inauguration in Washington.

Reuters with Fairfax Media