Ex-BHS boss Sir Philip Green has accused Frank Field of turning a parliamentary inquiry into the collapse of the high street chain into a "kangaroo court".
In a strongly-worded letter to the MP, who is the chairman of the Work and Pensions Select Committee, Sir Philip restated he had not broken any laws and said the MP had tried to create a "false narrative".
He added there had been "real progress" with the Pensions Regulator towards a solution to the BHS pension fund but stressed he was under "no legal liability".
Sir Philip is facing mounting pressure to be stripped of his knighthood and to rectify the black hole in the fund after an excoriating joint report by two Commons select committees.
The two committees - Work and Pensions and Business, Innovation and Skills - accused the entrepreneur of seeking to blame anyone but himself for the firm's failure.
His letter come after Mr Field gave an interview in The Times on Saturday in which he said he had "mis-read" the retail magnate and suggested "why the hell doesn't he just sign the cheque?"
Sir Philip's letter, which runs to more than 650 words, said: "I have tried to stay silent in the face of your regular outbursts and to focus on the important task of working towards a solution for the BHS pensioners. But I am not prepared to continue to allow your abuse to go unanswered.
"Even before the parliamentary inquiry started hearing from witnesses, you turned it into little more than a kangaroo court, with your constant press campaign barracking and insulting me and my family and your announcement from day one that the predetermined result of the inquiry was that I either sign a large cheque or lose my knighthood.
"Much as you would love to, you cannot point to any rules or laws that I have broken. Because I have broken none. You hide behind parliamentary privilege by publicly traducing me and my family in select committee hearings with allegations of theft.
"Your repeated attempts to lead the public into thinking that it is simply a matter of me writing a cheque are utterly disingenuous."
The latest twist also comes after lawyers acting for Sir Philip wrote to Mr Field over his comments in a BBC Radio 4 Today programme interview.
Mr Field said Sir Philip is "much worse" than media mogul Robert Maxwell, who raided the pension pot of the Mirror Group newspaper business.
He described Sir Philip as a "Napoleon figure" floating around on his yacht, having "orchestrated" an "old-fashioned classical asset-stripping" which has put the jobs of 11,000 BHS workers at risk and left 22,000 pensioners with a risky future.
A letter from legal firm Schillings said Mr Field had made a "highly defamatory and completely false" allegations about Sir Philip and money from the pension funds of the BHS and Arcadia retail groups.
In his own letter, Sir Philip said "defamatory remarks" by Mr Field put a solution "at risk" and the process and timetable for solving the issue was set by the Pensions Regulator, although he admitted it was "cumbersome and slow".
He also suggested the veteran Labour MP for Birkenhead was "privately backpedalling" by instructing lawyers to clarify he did not make some of the reported allegations.
Sir Philip added: "But you should be in no doubt, Mr Field, that any solution relies on a voluntary decision on our side to support the BHS pension schemes. There is no legal liability to make any payment to support the schemes.
"Indeed, I am unaware of any precedent for any private company or individual doing so."
Sir Philip concluded: "If you continue to seek to usurp the Pension Regulator's role with your characteristically unfathomable statements and hurl daily abuse at us, any failure to arrive at a pensions solution will be down to you. The BHS pensioners can only hope that you now rein yourself in."