Fugitive auto tycoon Carlos Ghosn's multiple arrests and detentions in Japan before he dramatically fled the country last year were "arbitrary", UN experts have ruled, urging Tokyo to pay him compensation.

In an opinion dated late last week and harshly condemned by Japan, the UN Working Group on Arbitrary Detention concluded that "the process of arresting and detaining Mr. Ghosn four times was fundamentally unfair".

The working group, made up of five independent experts who do not speak on behalf of the United Nations and whose opinions are not binding, stressed that its findings did not pertain to the accusations against Ghosn, but only to the conditions surrounding his detention.

It ruled that the now 66-year-old's detention was "arbitrary", and also voiced concern that his bail conditions had been "unusually strict", especially during the second period when he was barred from all contact with his wife, other than through lawyers.

The experts called on Tokyo to "take the steps necessary to remedy the situation of Mr. Ghosn without delay".

"The appropriate remedy would be to accord Mr. Ghosn an enforceable right to compensation and other reparations, in accordance with international law," it said.

The ex-Nissan chief's lawyers Francois Zimeray and Jessica Finelle hailed the "courageous decision", saying it represented "a decisive turning point."

But the Japanese government slammed the findings, saying it "deeply regrets" that the experts had "rendered opinions based on limited information and biased allegations", and not on "accurate understanding on Japan's criminal justice system."

"The opinion is totally unacceptable."

"The process of arresting and detaining Mr. Ghosn four times was fundamentally unfair," the UN experts said
"The process of arresting and detaining Mr. Ghosn four times was fundamentally unfair," the UN experts said AFP / ANWAR AMRO

Ghosn was dramatically arrested over financial misconduct allegations in November 2018 as he stepped off his private jet in Tokyo.

He was granted bail after a few months, but was rearrested three more times, spending a total of 130 days in detention, before eventually smuggling himself out of Japan and fleeing to Lebanon, arriving in Beirut on December 30.

Brazilian-born Ghosn, who also holds French and Lebanese citizenship, has denied the allegations against him.

The UN working group has no power to compel states to follow its rulings, but its decisions carry reputational weight.

In their opinion, the experts urged Japan "to ensure a full and independent investigation of the circumstances surrounding the arbitrary detention of Mr. Ghosn, and to take appropriate measures against those responsible for the violation of his rights."

It requested that Tokyo within six months inform it of whether such an investigation had been undertaken and whether Ghosn had received compensation or reparations.

In its statement Monday, the Japanese government said it would provide the working group with some details to help it rectify a number of "obvious factual errors", including on the time Ghosn had spent in detention without being brought before a judge.

But it stressed that it was inappropriate for the working group to have considered the case, insisting it was common practice to detain suspects likely to destroy evidence or skip bail.

"Flight from a criminal trial, in violation of the conditions a defendant promised to respect upon his or her release on bail, is not condoned under any nation's legal system."

The working group's findings, it warned, could "encourage those who would stand criminal trial to entertain the idea that flight can be justified and prevent the realisation of justice and the proper functioning of the criminal justice system in each country."