Banks held a series of undisclosed meetings with Russian embassy officials around the time of the 2016 referendum campaign, according to reports in the Observer and Sunday Times (how the story broke is a sub-plot in itself).
The last of these was in November 2016, three days after Mr Banks, Leave.EU's communications director Andy Wigmore and the former UKIP leader Nigel Farage met Mr Trump in NY following his election victory.
Mr Banks categorically denied any wrongdoing in meeting with Russian officials, insisting his meetings had focussed on Donald Trump more than Brexit and that Russian money had never been transferred to Leave.EU.
In total, Mr Banks said he had two lunches with the Russian ambassador and one cup of tea where he was introduced to a businessman with the gold mines proposal.
The two will appear before the Commons culture and media committee on Tuesday to answer questions about alleged Russian involvement in the European Union referendum campaign, having initially pulled out of a hearing on Friday.
Mr Banks is also said to have given Russian officials telephone numbers for members of Donald Trump's presidential transition team, just days after he and Mr Farage visited Trump Tower in the wake of the shock United States election result. Lunch with the Russian ambassador?
The Leave.EU funder added that if there was any attempt at Russian interference in the 2016 referendum, then it was at an "amateur level". "There is no evidence".
Asked if there was any Russian money given to Leave.EU, Mr Wigmore insisted: "No, not one penny or one rouble".
"This whole fake news narrative started to roll from it". It had not been mentioned.
"It was only when Trump won that there had to be a reason why he had won and Brexit happened".
Damian Collins, the Tory chairman of the committee, said to the paper: 'I think we have a right to know what the level of that contact [with Russia] was.
Home Secretary Sajid Javid has said the government is "very seriously" examining Arron Banks and Andy Wigmore's links to Russian Federation as the Brexit-backing pair face quizzing from MPs today.
Leave.EU was fined £70,000 by the Electoral Commission earlier this year for breaches of election law in the Brexit referendum.
Banks reiterated the point on Tuesday and said the claims against him had come from people whom he did not regard as credible witnesses.