Former Nissan CEO will likely remain in jail for six months or more, according to new reports.

Carlos Ghosn, the former CEO of Nissan, has appeared in court for the first time after his arrest in Japan.

Ghosn was arrested on November 19, 2018 after he was accused by Nissan of a number of misdemeanours during his time at the automaker.

He has been formally charged for under reporting his income by over $100 million, shifting his currency trading losses to his employer, and misusing company funds.

Automotive News said Ghosn appeared in court wearing a suit, green slippers and handcuffs. His lawyer, Motonari Otsuru, indicated Ghosn has been moved to a larger cell with a western-style bed.

Ghosn looks likely to be charged with new crimes later this week. As is common in Japan, the former Nissan CEO will probably be held without bail until his trial starts. Visitation rights are limited, and he can be interrogated at length without the presence of his lawyers.

In a statement to judge Yuichi Tada, Ghosn said he was "innocent of the accusations" and had "always acted with integrity and [has never] been accused of any wrongdoing in my several-decade professional career".

Addressing charges he underreported his income for eight years until March 2018, Ghosn said he kept track of how much he could have been paid elsewhere as "an internal benchmark ... for my own future reference", but this data was never shared with other directors.

He admitted there were "various proposals for non-compete and advisory services post-retirement", but he "never received any compensation from Nissan that was not disclosed", nor was there "any binding contract ... to be paid a fixed amount that was not disclosed".

As for shifting his loss-making currency trading contracts to Nissan, Ghosn confirmed his bank had asked him to stump up more collateral at the height of the Global Financial Crisis.

At this point, he said he faced two options: quit Nissan and use his retirement allowance as collateral, or "ask Nissan to temporarily take on the collateral, so long as it came to no cost to the company".

After Ghosn found his own collateral, the contracts were transferred back to Ghosn without the company incurring any loss.

According to Automotive News, Nissan has accused Ghosn of using money from the company's "CEO reserve fund" to pay Saudi firm Khaled Juffali to help secure the necessary collateral.

The former CEO stated Khaled Juffali was paid for "critical services", including helping the company purchase a significant stake in the Nissan's distributor in Saudi Arabia.

Otsuru, Ghosn's lead lawyer, admitted Khaled Juffali extended Ghosn ¥3 billion ($39 million) in collateral during the financial crisis, but this assistance was unrelated to later payments from Nissan.

Ghosn said he used currency contracts as his family lived in the States, but he couldn't be paid in US dollars for his work at Nissan.

In his closing remarks Ghosn said he had "dedicated two decades of my life to reviving Nissan and building the Alliance", and the turnaround of the company is "the greatest joy of my life, next to my family".

Noting his loyalty to the company, he said he had been approached to lead four other companies, including GM and Ford, during his tenure at Nissan, but remained with the "iconic Japanese company that I care deeply about".

At the time of his arrest he was the chairman of Nissan and Mitsubishi Motors, as well as the CEO of Renault and the Renault Nissan Mitsubishi Alliance.

He has since been removed as chairman of the two Japanese automakers, although he remains a non-representative director at Nissan. Renault has appointed a temporary CEO while Ghosn remains in custody, and the CEOs of Renault Nissan and Mitsubishi have agreed to share the top job at the overarching alliance.

His co-accused, Nissan director Greg Kelly, was released on bail before Christmas.