The Tokyo District Court said Friday that it had extended former Nissans board chairman Carlos Ghosn's detention until April 22 to allow prosecutors time to bring formal charges against him or let him free.
Ghosn was initially detained in November on suspicion of conspiring to understate his Nissan income by about 50 percent between 2010 and 2015.
He was released on bail in early March and then re-arrested last week in connection with new allegations that some $35 million was diverted from Nissan to an Oman dealership.
Japanese media have reported that some of the money from the Oman dealership may have gone to a company, Beauty Yachts, run by Ghosn's wife Carole, while other money may have gone to a U.S.-based startup called Shogun, owned by Ghosn's son.
On Thursday, Carole Ghosn, who had been in France, returned to Tokyo for questioning.
Long detention and multiple arrests are common in Japan, but re-arresting a person who cleared bail is rare.
Ghosns lawyers have protested his detention as unfair.
Last week, Nissan ousted Ghosn from the board and appointed French partner Renault SA's chairman Jean-Dominique Senard to replace Ghosn. Renault owns 43 percent of Nissan.