The former Ukip donor – whose second and third meetings with Alexander Yakovenko were only disclosed in leaked emails – revealed he had acted as a link between Moscow and the presidential candidate’s advisers.
Mr Banks insisted it was the “only thing” of significance that came out of the meetings – “because the Russians wanted to get hold of the transition team”.
Leave.EU spokesman Andy Wigmore, asked if the campaign, bankrolled by Mr Banks, had ever accepted money from the Russian government, replied: “Nyet.”
Mr Wigmore also told the “fake news” inquiry that he and Mr Banks handed the Trump team telephone details for No 10 after his victory which, remarkably, it did not have.
The pair were giving evidence after it was revealed they met Russia’s ambassador to the UK three times in 2015 and 2016 – rather than the single “six-hour boozy lunch” Mr Banks had previously acknowledged.
Emails leaked to The Observer and The Sunday Times also showed the ambassador asked by him if he was interested in participating in a Siberian goldmine deal.
Mr Banks admitted he met with the businessman behind the goldmines, telling the MPs: I’m a businessman, why shouldn’t I? I thought it was interesting.”
But he said he was persuaded it was too risky to invest, insisting: “I have got no business interests in Russia and I have done no business deals in Russia”
Mr Wigmore told the digital, culture, media and sport committee he first met with the Russians in his role as a diplomat for the South American country of Belize.
“I was trying to find investors to look at perhaps buying a banana farm which had got into trouble because of its owner … and, as a consequence, Belize couldn’t sell its bananas in places like the United States or the United Kingdom,” he said.
“It needed someone to buy them. One of the conversations we had was about that. There was a myriad of things we wanted to talk to them about… it wasn’t anything to do with politics.”
Mr Banks rejected allegations that Leave.EU may have used data gathered by his insurance company Eldon during the referendum campaign – and illegally sent data abroad.
In April, a former Cambridge Analytica director said Big Data Dolphins, a company set up by Mr Banks, worked with a data science team at the University of Mississippi on information relating to UK citizens.
But Mr Banks said: “No data has been sent to Mississippi – the project hadn’t even started.” He added: “We have not sent data anywhere.”
During the session, Mr Banks and Mr Wigmore repeatedly admitted they had “exaggerated” the capabilities of the Leave.EU campaign – the latter calling himself an “agent provocateur”.
“We were not above using alternative methods to punch home our message or lead people up the garden path if we had to,” Mr Banks said.
And, assessing the deadlock in the Brexit negotiations, he said: “It’s almost like a prisoner where the door is open and the prisoner is scared to leave the prison cell. It has been 45 years of institutionalised brainwashing.”
Later, the pair walked out of the hearing before the MPs had finished their questions after the committee overran, saying they had a lunch appointment they “didn’t want to be late for”.
It then emerged it was with two DUP MPs, after Ian Paisley said he had an “entertaining lunch” with the pair, adding there was “no caviar or vodka” in reference to the row over their contacts with Russia.
Mr Paisley tweeted a picture of the group, along with fellow DUP MP Sammy Wilson, on the House of Commons terrace.