Carlos Ghosn has declared his innocence.
On Tuesday (January 8) the ousted Nissan chief made a first public appearance since his November arrest.
He told a Tokyo court he was quote "unfairly detained based on meritless and unsubstantiaed accusations" and that he had properly reported his compensation from Nissan.
Ghosn, taken in on the 19th of November, has been formally charged with mis-reporting his income.
Since then he's been re-arrested twice on further charges.
Reuters Malcolm Foster is in Tokyo.
SOUNDBITE (ENGLISH), REUTERS' MALCOLM FOSTER SAYING (ENGLISH):
"The presiding judge said that Ghosn was considered a flight risk and that if he was released he might hide some of the evidence, so that was the main reason they were keeping him in detention. This is a very typical practice in Japan - to keep suspects in detention for long periods. Japanese law allows suspects to be held for 23 days without charges and then even after that they can be held until and through the trial, which happens quite frequently".
Nissan quickly shot back at Ghosn's claims.
The company said it had uncovered substantial evidence of misconduct, after an informant prompted an investigation.
But at a separate news conference, Ghosn's lawyers said the company HAD agreed to take on his personal foreign exchange contracts.
They also expressed concern over how long he might be held:
SOUNDBITE (JAPANESE) LEAD LAWYER FOR FORMER NISSAN CHAIRMAN CARLOS GHOSN'S LEGAL TEAM, MOTONARI OTSURU, SAYING:
"I'm afraid it will take at least another six months until the first trial takes place."
The case has rattled Nissan's alliance with Renault.
Ghosn remains chairman and CEO at the French automaker.
He had been pushing for a deeper tie-up with Nissan at the French government's urging.
The idea had provoked opposition within the Japanese firm.