Japanese prosecutors have charged former Nissan chairman Carlos Ghosn with financial misconduct, accusing him of under-reporting his pay package over a five-year period.
He has also been re-arrested on further allegations of under-stating his pay, which is likely to keep him in detention until 30 December.
Mr Ghosn has previously denied the accusations.
Prosecutors have also charged Nissan in relation to the case.
Mr Ghosn was arrested in November after the allegations first surfaced. Monday was the last day he could be held by authorities before he either had to be charged or released.
His defence team say the accusations against Mr Ghosn are invalid because they do not relate to his salary, but to future payments that he was expected to receive after retirement.
Nissan said it was taking the situation “extremely seriously”.
“Making false disclosures in annual securities reports greatly harms the integrity of Nissan’s public disclosures in the securities markets, and the company expresses its deepest regret,” the carmaker said in a statement.
A source close to the firm said that the charges were not unexpected “given the company flagged its concerns” to prosecutors after it had conducted an internal investigation.
If Mr Ghosn is convicted, the charges could mean up to 10 years in prison. The charges also carry a fine of up to 700m yen ($6.2m; £4.9m), according to the Japanese regulator, the Securities and Exchange Surveillance Commission.
Originally, prosecutors said that Mr Ghosn and senior executive Greg Kelly – who has also been charged with financial misconduct – had conspired to understate Mr Ghosn’s pay from 2011 to 2015. The fresh charges, issued on Monday, allege they did the same thing from 2016 to 2018.
From 2010, Japanese firms have been required to disclose the salaries of executives who earn more than 100m yen ($888,000; £697,000).
Brazil-born Mr Ghosn, aged 64, known as the Le Cost Killer for his radical approach to restructuring, was the architect of the Renault-Nissan alliance, and brought Mitsubishi on board in 2016. In the past, he has been hailed a hero in Japan for turning around the ailing Nissan.
French car maker Renault was seen as the dominant partner due to its 43% shareholding in Nissan, despite selling fewer vehicles. Nissan’s shareholding in Renault is only 15%.
Sources close to Mr Ghosn have previously described the accusations as a “clinically planned hatchet job”, arguing they were aimed at resetting the balance of power in the carmakers’ alliance.
While the governments of Japan and France insisted that the alliance of companies that manufactured 10 million cars last year should be preserved, it is widely thought that Nissan executives were uncomfortable at the power wielded over the company by Renault and concentrated in the hands of Mr Ghosn.
Nissan and Mitsubishi both sacked Mr Ghosn as chairman after the arrest last month.
But Renault has held off doing so, saying he would remain as its chairman and chief executive, but has appointed a temporary deputy chief executive to take over the running of the firm.