Carlos Ghosn has proclaimed his innocence in his first public appearance since the former Nissan chairman was arrested in November for alleged financial misconduct.

Dressed in a dark suit, but without a tie, Ghosn, who appeared to have lost weight during his 50 days in detention, told the Tokyo district court in a special hearing on Tuesday that he had been “wrongly accused” of under-reporting his salary for several years. He had been led into the courtroom in handcuffs, which were later removed.

“I have always acted with integrity and have never been accused of any wrongdoing in my several-decade professional career. I have been wrongly accused and unfairly detained based on meritless and unsubstantiated accusations,” the 64-year-old, whose hair was greying at the roots, told a packed courtroom.

He added: “Contrary to the accusations made by the prosecutors, I never received any compensation from Nissan that was not disclosed, nor did I ever enter into any binding contract with Nissan to be paid a fixed amount that was not disclosed.”

His lawyer had demanded the court justify his client’s continued detention in connection with a case that has shaken the Japanese carmaker’s alliance with Renault and prompted criticism of Japan’s treatment of suspects.

Ghosn was first arrested on 19 November and later charged on suspicion of under-reporting his salary by 5bn yen ($44m) over five years until 2016 – allegedly to avoid accusations from Nissan staff that he was overpaid. He has consistently denied the allegations.

He has since been twice rearrested – but not charged – over allegations that he continued to file false pay reports and had transferred personal investment losses of 1.85bn yen to Nissan.

Tuesday’s hearing, a right granted to suspects by Japan’s postwar constitution, does not mark the official start of Ghosn’s trial, nor will it have an impact on his case, according to legal experts.

His lengthy stay in a tiny, freezing cell at the Tokyo detention centre has drawn international criticism of Japan’s “hostage justice”, which allows prosecutors to re-arrest suspects several times over different allegations and to question them for up to eight hours a day without a lawyer present.

Ghosn’s courtroom appearance attracted huge media attention, with cameras ranged along the streets to capture his departure from the detention centre and arrival at court. More than 1,000 people had queued outside the courtroom to draw lots for the 14 seats in the public gallery.

His latest period of detention expires on Friday.

The Frenchman, who was born in Brazil and is of Lebanese descent, was once hailed as Nissan’s saviour for masterminding its stunning turnaround in the late 1990s and for forging a three-way alliance with Renault and Mitsubishi Motors.

He was sacked as chairman of Nissan – which has yet to appoint a permanent replacement – soon after his arrest but kept on as head of Renault.

The scandal has exposed differences between the French carmaker and its partners in Japan over Ghosn’s alleged conduct that some industry observers say could threaten the alliance.

But in an interview with Agence France-Presse on the eve of the hearing, Nissan’s chief executive, Hiroto Saikawa, dismissed speculation that the scandal risked destroying the alliance. “I don’t think it’s in danger at all,” he said.

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