Nigel Farage is a "person of interest" in the US intelligence investigation into possible collusion between Russia and Donald Trump's presidential campaign, the Guardian has reported.

Sources said to have knowledge of the investigation told the newspaper the former Ukip leader had attracted the strong interest of FBI investigators because of his links with individuals in the Trump campaign and Wikileaks founder Julian Assange, whom Farage visited in March.

Wikileaks was accused by former CIA director John Brennan of being in collusion with the Kremlin via third parties by publishing hacked emails that damaged Hillary Clinton's presidential campaign.

Farage – who dismissed the Guardian's story as "fake news" – has reportedly not been accused of wrongdoing and is not a suspect or a target of the US investigation.

Being a person of interest meant investigators believe Farage may have information about acts under investigation, sources told the Guardian.

"One of the things the intelligence investigators have been looking at is points of contact and persons involved," one source said. "If you triangulate Russia, WikiLeaks, Assange and Trump associates the person who comes up with the most hits is Nigel Farage.

"He's right in the middle of these relationships. He turns up over and over again. There's a lot of attention being paid to him."

Farage Trump
Donald Trump and Nigel Farage grin as they meet at Trump Towers in New York on 13 November 2016 Twitter/@Nigel_Farage

A spokesman for Farage reportedly did not respond to the Guardian's questions about whether Farage was aware of the FBI inquiry; had hired a lawyer in connection to the matter; or whether Farage had been paid for appearances on the Russian state-backed media group RT.

They instead described the claims about Farage's activities as "verging on the hysterical".

Farage later said in a statement: "This is fake news. In response to the Guardian article, it has taken me a long time to finish reading because I am laughing so much.

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

"For the record I have never been to Russia, I've had no business dealings with Russia in my previous life and I have appeared approximately three times on Russia Today in the last 18 months. I consider it extremely doubtful that I could be a person of interest to the FBI as I have no connections to Russia."

The investigation into Trump concerns whether his campaign officials and those close to the billionaire property tycoon colluded with Russian officials to try influence the US presidential election result.

The close relationship between Trump and Farage is well known, with the ex-Ukip leader becoming the first foreign politician to meet and celebrate with the former reality TV star following his victory in the the US election.

Trump even later suggested Prime Minister Theresa May should make Farage the UK's ambassador to the US.

The Guardian said the FBI was examining Farage's links to Roger Stone in particular, the president's long-time political adviser who has admitted being in contact with hacker Guccifer 2.0 – believed by US intelligence to be a Kremlin agent.

Farage, a serving MEP, has also faced questions in the past over his relationship with Assange.

He insisted his reason for visiting the Wikileaks founder earlier this year at the Ecuadorian embassy in London, where he lives in exile, was for "journalistic reasons".

When asked to elaborate, he told the German newspaper Die Zeit: "I will not say any more about that ... It has nothing to do with you. It was a private meeting."

Farage has now said that meeting "was organised for me by LBC Radio with a view to conducting an interview".

His spokesman told the Guardian he had only met Assange in person on that one occasion. He did not say how long they had known each other, however.

Farage has voiced support for the Russian president in the past, calling Vladimir Putin the world leader he most admired in a 2014 interview.

While praising Putin at the time for his actions in Syria, he said he did not approve of Russian leader politically, however.