Gianni Paladini has hit back at Peter Pannu after the Birmingham City chairman implied the Italian's consortium does not have enough money to buy the club.
Paladini's group - who planned a swift move into St Andrew's - said they tabled an offer worth around £30million which was dismissed by Pannu who is in control of negotiations.
And Paladini, after hearing the Hong Kong businesman's rant, challenged the Blues acting chairman to let them prove themselves.
"Mr Pannu has insulted me and our backers by saying we don't have the money," said Paladini.
"Now, prove me wrong, Mr Pannu, by providing us exclusivity for two weeks to finalise the deal at the original price that was offered - and agreed.
"If we are unable to do so, you can then show I am wrong."
Pannu previously told the Hong Kong media: "If people don't have the money, they should just shut up.
''I support freedom of speech and he [Paladini] can say what he likes in the press, but if anyone wants to buy our club they better prove they've got the money to do it before they talk to the British media.
"There's been a complete misrepresentation that he's closing in on a purchase and it's totally without foundation.
''We need to put a stop to this nonsense. He's just trying to get the club on the cheap."