Prominent Brexiteer Arron Banks has insisted there is no evidence the anti-EU campaign took Russian money as he faces a grilling form MPs.
Millionaire Leave.UK founder Mr Banks and the organisation's communications chief Andy Wigmore have promised "fireworks" when they appear before the Commons Digital, Culture, Media and Sport Committee's fake news inquiry on Tuesday.
Mr Banks agreed to give evidence to the committee after previously pulling out as he accused MPs of conducting a "witch hunt".
His appearance comes after Prime Minister Theresa May said calls for an inquiry into alleged links between Russia and the campaign to leave the European Union are a matter for the police.
Reports in the Sunday Times claimed Mr Banks held a series of undisclosed meetings with Russian embassy officials around the time of the 2016 referendum campaign.
The paper said it had seen emails showing he also discussed a potential business deal involving six Russian gold mines with ambassador Alexander Yakovenko after being introduced to him by a suspected Russian spy.
Responding to calls for a police inquiry on Nigel Farage's LBC radio show, Mr Banks said: "What's the crime? I would like to know what the police are going to investigate - lunch with the Russian ambassador?
"Where's the evidence we took Russian money? There's no evidence."
Mr Banks said he first met the Russian ambassador over a "boozy lunch".
"We had about four shots of Stalin vodka, brandy, wine. We were pretty trolleyed. The ambassador was probably in a worse state than we were," he said.
He told Mr Farage there was another lunch meeting and a "cup of tea", where he was introduced to a businessman involved in the Russian gold mines, but denied using the Brexit campaign to further his business interests.
Asked about allegations he was reporting back to the Russians three days after meeting newly elected Donald Trump, he said: "It's complete nonsense."
Asked if there was any Russian money given to Leave.EU, Mr Wigmore insisted: "No, not one penny or one rouble."