Japan on Sunday said it would tighten immigration measures after former Nissan boss Carlos Ghosn fled the country while on bail, its first official response to an astonishing escape that has transformed the executive into an international fugitive.

Former Nissan chairman Carlos Ghosn leaves the Tokyo Detention House following his release on bail in Tokyo on Wednesday. Ghosn posted bail of 1 billion yen ($9 million) in cash, paving the way for his release from the detention centre after more than three months in custody. Photo: AFP

Ghosn revealed on Tuesday that he had fled to his childhood home of Lebanon to escape a "rigged" justice system in Japan. The former Nissan Motor and Renault chairman was arrested in Tokyo in November 2018 and faced multiple charges of financial wrongdoing, which he denies.

Justice Minister Masako Mori said Ghosn's "apparently illegal" departure was very regrettable and added there was no record of him leaving the country. She promised a thorough investigation and said authorities had issued an international notice for his arrest.

"I have instructed the Immigration Services Agency to coordinate with related agencies to further tighten departure procedures," she said, adding that Ghosn's skipping bail was not justified, and that the court had revoked his bail.

Separately, prosecutors issued a statement defending Japan's justice system, saying his departure ignored the legal system and amounted to a crime.

Authorities have remained mum for days following the events of Ghosn's escape, with all government offices and most businesses shut for the New Year holidays.

As such, it remains unclear what Japan might do to bring him back. It has extradition treaties only with the United States and South Korea, meaning it might be difficult to return Ghosn from Lebanon.

Lebanon this week said it had received an Interpol arrest warrant for Ghosn. It has said he entered the country legally.

A senior Lebanese security official said that it was not yet clear whether Ghosn would be summoned for questioning over the warrant or not, but added that Lebanon does not extradite its citizens.

The Wall Street Journal reported on Friday that Ghosn slipped out of Japan aboard a private jet hidden in a large black case typically used to carry audio gear. He was accompanied by a pair of men with names matching those of American security contractors, the newspaper said, citing people familiar with an investigation into the escape.

A Turkish private jet operator has said two of its planes were used illegally to carry Ghosn, with an employee falsifying the lease records to exclude the executive's name.