TOKYO — Mitsubishi Motors has joined Nissan in accusing Carlos Ghosn of financial wrongdoing, saying on Friday that he secretly received compensation of 7.8 million euros, or almost $9 million, from a joint venture of the two automakers.

Osamu Masuko, Mitsubishi’s chief executive, told reporters in Tokyo that the automaker was considering suing Mr. Ghosn, the former chairman of both Nissan and Mitsubishi. Renault, the third automaker in the global car alliance that Mr. Ghosn ran, is also preparing to cut ties with its star executive.

Mr. Ghosn has been detained in Tokyo since Nov. 19 on suspicion of understating his salary for eight years, and of temporarily transferring personal investment losses to Nissan’s books during the 2008 financial crisis. Mr. Ghosn has denied all charges. His lawyers could not immediately be reached for comment.

Mitsubishi’s findings involve a joint venture between Nissan and Mitsubishi established in 2017 in the Netherlands. The company said Mr. Ghosn, who is listed as a director of the joint venture, had drawn up an employment contract that rewarded him €7.8 million in compensation.