Michael Woodford was sacked by Olympus on Friday just two weeks after the company promoted the Briton from his role as president.
Mr Woodford accuses the board of firing him for probing allegations of improper payments related to acquisitions.
Explaining the reasons for Mr Woodford’s dismissal, Olympus says he had “largely diverted from the rest of the management team in regard to the management direction and method, and it is now causing problems for decision-making by the management team”.
But Michael Woodford claims that unknown parties in the Cayman Islands received payments of $675m, or 36.1 per cent of the transaction price.
Olympus is threatening to sue Mr Woodford over his comments but the 51-year-old said he has nothing to fear: “If they would like to come to London, to the high court, and go through this I’d be more than delighted. I’d relish it. Please serve the papers on me tomorrow. I would love that.”
According to an Olympus investor, who wishes to remain anonymous, Hisashi Mori, executive vice-president at Olympus, said: “He (Mr Woodford) has disclosed information that a director should not be revealing and it’s a very serious problem for the management of the company.”
Mori has claimed that the amount paid, which included cash and options, was less than half the amount claimed by Mr Woodford. Mori nonetheless conceded that the fee was high, while he declined to give an exact figure.
Olympus shares plunged by one-quarter on Monday following an 18 per cent fall last week.
The stock plunge has wiped out $3.2bn in market value from the Japanese precision instrument and camera maker.
Mori reiterated the company’s statements last Friday that Woodford was ousted because of irreconcilable differences in management approach and for Woodford’s insistence on circumventing business managers.