A French judge investigating Tokyo's alleged vote-buying around its bid to host the 2020 Olympics has labeled a Japanese probe into the claims "limited" and having "many flaws," Kyodo News learned Saturday.

The preliminary judge made the observation in Paris in December 2018 when questioning Tsunekazu Takeda, then president of the Japanese Olympic Committee who also headed the Tokyo Olympic bid committee, sources with knowledge of the matter said.

BUENOS AIRES, Argentina - (From L) Then Japanese Prime Minister Shinzo Abe, former International Olympic Committee President Jacques Rogge, disgraced Tokyo bid chief Tsunekazu Takeda and former Tokyo Gov. Naoki Inose are seen at a signing ceremony in Buenos Aires on Sept. 7, 2013, after Tokyo was chosen as the host city of the 2020 Summer Olympics at the International Olympic Committee's general session. (Kyodo)

It is the first time details about the exchange between the judge and the 73-year-old Takeda have come to light. A special investigative team from the Tokyo District Public Prosecutors Office questioned Takeda and others in 2017 at the request of the French authorities.

In the eyes of the French investigators, their Japanese counterparts' probe was unsatisfactory, with the preliminary judge quoted by the sources as telling Takeda that Japanese prosecutors "failed to question all the witnesses or seize documents" that had been requested from the French side.

This was due to a difference in the penal code between the two countries, the judge said. Under French law, bribery of private citizens and public officials is illegal whereas in Japan such a transaction is only considered bribery if a public official is a recipient.

The French investigator then interrogated Takeda on how he was involved with the bid committee's awarding of a consultancy deal to Black Tidings Co.

The now-defunct consulting firm based in Singapore received a total of more than 200 million yen ($2 million) from the bid committee in July and October 2013, or shortly before and after the Japanese capital was picked in September that year as the Olympic host city, defeating Istanbul and Madrid.

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The judge also questioned Takeda over whether he had been aware of a close relationship between Black Tidings owner Tan Tong Han and Papa Massata Diack, a Senegalese national and the son of Lamine Diack, disgraced former head of track and field's world governing body.

Undated photo shows Papa Massata Diack, son of former head of the International Association of Athletics Federations Lamine Diack. (Kyodo) ==Kyodo

Lamine Diack was also a member of the International Olympic Committee and said to have had influence over African votes at the time of the Tokyo bid.

The French side also demanded Takeda hand over the bid committee's contract documents and reports it received from Black Tidings.

In response, Takeda insisted he had played no role in choosing Black Tidings as the bid committee's consultancy firm, saying it was a result of recommendations from Japanese advertising giant Dentsu Group Inc. The former Olympic equestrian athlete also said he had no knowledge of the relationship between Tan and the younger Diack.

When the French judge pointed out it was "unnatural" for the bid committee chief not to have been informed of Tan and Papa Massata Diack's relationship by "Dentsu, which had long worked with the pair," Takeda said, "It was not me who received recommendations" from the advertising firm.

"I approved the conclusion of the contract because I had every confidence in the secretariat" of the bid committee, Takeda was quoted by the sources as responding.

Takeda stepped down as head of the JOC in June 2019 after French authorities confirmed earlier in the year that they had started an official investigation into alleged corruption over Tokyo's bid.

Takeda, the great-grandson of Emperor Meiji, told Kyodo News through his lawyer that he is "innocent, as I said to the French judge."

"It is true that I signed off the contract with Black Tidings as the final decision-maker, but I was not involved with the selection of all the consultants," he said.