Britain's Nigel Farage, a leading Brexit campaigner, is a "person of interest" in the US investigation into possible collusion between Russia and Donald Trump's presidential campaign, the Guardian newspaper reported, citing unidentified sources.

The British newspaper said Mr 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 had "raised the interest" of FBI investigators because of his relationships with individuals connected to both the Trump campaign and Wikileaks founder Julian Assange.

Mr Farage has moved to distance himself from the reports.

The former UKIP leader and serving MEP described the Guardian's report as "hysterical" and claimed it is "extremely doubtful" he could be a person of interest as he has "no connections" to Russia.

Mr Farage, in a statement to the Press Association, also said he met WikiLeaks founder Julian Assange "with a view to conducting an interview".

In a statement titled "fake news", Mr Farage said: "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 RT (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.

"My meeting with Julian Assange was organised for me by LBC Radio with a view to conducting an interview."

Mr Farage's office said he would be making no further comment on the matter.

Close aides to Donald Trump subpoenaed over Russia ties

The US House Intelligence Committee has issued subpoenas to President Donald Trump's personal lawyer and his former national security adviser.

The committee has ordered lawyer Michael Cohen and former security adviser Michael Flynn to appear before them and supply documents.

The committee is mounting one of several probes into alleged meddling by Moscow in last year's presidential election, and any collusion with the Trump campaign.

While Mr Flynn has been a known target of congressional and Justice Department investigations into possible collusion between Moscow and the Trump presidential campaign, Mr Cohen has only recently become a focus of the probe, for unknown reasons.

Mr Cohen spent years as the main lawyer for the Trump Organisation, the president's New York-based real estate and entertainment business.

He was also mentioned as someone with Russian contacts in the still-unverified dossier on Trump campaign ties to Russia compiled by former British intelligence agent Christopher Steele.

Besides Mr Cohen and Mr Flynn, the investigations are believed to be examining Mr Trump's son-in-law, Jared Kushner, former campaign chairman Paul Manafort, former political advisor Roger Stone, and former foreign policy consultant Carter Page.