Even as the shock waves from the arrest of Nissan's once-revered chairman Carlos Ghosn for understating his compensation continue to linger, the latest buzz is that the alleged financial misconduct may be far bigger than initially suspected.

A day after the 64-year-old was unanimously ousted from the Chairman's position by Nissan Motor Co's board, Ghosn is reportedly set to face a new charge from prosecutors for under-reporting his income by a total of $71 million, AFP reported. That's 61% more than the amount he was previously accused of.

Prosecutors had intercepted the Brazil-born tycoon on Monday as he landed in Tokyo on a private jet, accusing him - as well as fellow executive Greg Kelly - of understating his income by around 5 billion yen ($44 million) between June 2011 and June 2015.

But according to the agency, Japanese media Asahi Shimbun and the Nikkei business daily today reported that Ghosn is now suspected of under-reporting his income by another three billion yen for the following three fiscal years. So prosecutors are reportedly now planning to re-arrest him on charges of understating his income by a total of 8 billion yen in the past seven years. Under Japanese law, arrested suspects can face additional arrest warrants, which can mean heavier charges.

The Nikkei reportedly said that Ghosn is further suspected of failing to report a profit of four billion yen through stock appreciation rights. The latter is a type of incentive plan that allows companies to give its management a bonus on strong earnings.

On Wednesday, prosecutors successfully applied to extend Ghosn's custody for an additional 10 days as they step up their questioning. He is being held custody in a Tokyo detention centre, where inmates are typically allowed 30 minutes exercise per day and only two baths a week. That's a steep fall from grace for the titan of the auto sector who is credited with not only turning around Nissan's fortunes but also forging the alliance with Renault and Mitsubishi Motors, which sold a combined 10.6 million cars last year - more than any other firm.

Nissan said on Monday an internal investigation triggered by a tip-off from a whistleblower had revealed that Ghosn engaged in other financial wrongdoing as well. The allegations include using Nissan's money to secretly buy and maintain a string of luxury homes across the world as well as help his sister. The Japanese media reported that Nissan had paid $100,000 a year as consulting fees to Ghosn's sister since 2002 although there is no record of her doing advisory work for the group. It is further alleged that the Brazil beachfront home that she was living in was bought with company money.

Meanwhile, the future of the fractious alliance between the auto brands - employing 450,000 people globally - hangs in balance. Yesterday, the French and Japanese finance ministers reiterated their "strong support" for the alliance at a meeting in Paris, adding that both wanted "to maintain this winning cooperation".

With agency inputs