By Kaori Enjoji, CNN Business

(CNN) -- Former Nissan boss Carlos Ghosn has again professed his innocence in a new video and accused executives at the Japanese carmaker of conspiring to remove him from power.

"This is about a plot, this is about conspiracy, this is about backstabbing," Ghosn said in the seven-minute video, which was recorded before he was arrested last week in Japan for a fourth time.

Ghosn, who once led a global autos alliance that consisted of Renault, Nissan and Mitsubishi Motors, claimed in the video that fears over a merger had prompted a revolt at Nissan and led to his ouster.

Neither Ghosn nor his lawyer, Junichiro Hironaka, offered a response to the latest allegations of financial misconduct that prompted the auto executive's arrest and return to jail.

Nissan declined to comment on the video, but a spokesperson for the company said an "internal investigation has uncovered substantial evidence of blatantly unethical conduct" by Ghosn.

"The company's focus remains on addressing weaknesses in governance that failed to prevent this misconduct," the spokesperson added.

Japanese prosecutors accused Ghosn last week of siphoning off $5 million in payments made by Nissan to a dealer that he controlled.

Ghosn is awaiting trial on separate charges that he understated his income for years and abused his position by transferring personal investment losses to Nissan. He has denied those charges.

"Unless Ghosn can offer evidence showing he did not steal from Nissan, his position is untenable," said Stephen Givens, who has been practicing law in Japan for more than 30 years.

"If the facts are as suggested, this is devastating for Ghosn," added Givens.

Hironaka told reporters that he would file a special appeal to Japan's Supreme Court on Wednesday, arguing that there was no reason for Ghosn's rearrest.

Ghosn is now back at the Tokyo jail where he was held for 108 days until he posted $9 million bail in March. Prosecutors can hold Ghosn until April 24, after which they must indict or release him.

His arrest and detention has led to scrutiny of Japan's judicial system, which allows suspects to be questioned without a lawyer. Prosecutors in Japan also boast an extremely high conviction rate.

Hironaka criticized the treatment of Ghosn on Tuesday, saying the morning raid that preceded his latest arrest was "inhumane."

Lawyers, including former public prosecutors, say that complaints of human rights abuse will do little to aid Ghosn's defense when his trial begins later this year.

Renault unveiled new allegations against Ghosn last week, claiming that expenses incurred by its former CEO and chairman involved "questionable and concealed practices" that violated its ethics rules.

The French carmaker also announced Ghosn's resignation from its board.

Asked Tuesday whether Ghosn had any regrets about the nearly 20 years he spent leading Nissan, Hironaka said:

"He's saying it is a conspiracy. He doesn't think there is anything to regret."

Nissan cut its last remaining ties with Ghosn on Monday when shareholders voted to oust him from the board.