SINGAPORE (AFP) - Singapore's Corrupt Practices Investigation Bureau (CPIB) says it is helping French authorities investigate possible fraud in Japan's Olympic bid after a company based in the city-state was linked to alleged irregularities.

French investigators say they suspect that US$2 million (S$2.74 million) paid to Papa Missata Diack, son of disgraced athletics supremo Lamine Diack, was aimed at getting support for Tokyo's 2020 Olympics bid.

They said two payments were made in 2013 to an account held by Black Tidings, a Singapore-based company linked to Papa Diack.

Diack Jr was employed by the International Association of Athletics Federations as a marketing consultant.

"The Corrupt Practices Investigation Bureau (CPIB) is working with the French authorities on this case," its said in an e-mailed response to AFP queries. "As investigation is still ongoing, we will not be able to comment further."

Singapore's CPIB is a government agency that investigates and prosecutes corruption in the public and private sectors.

The payments to a bank account in Singapore were first revealed by Britain's Guardian newspaper, and prompted French prosecutors to launch a probe on Thursday.

Sources told AFP that investigators suspected the money was aimed at helping Tokyo secure the 2020 Games.

Late on Friday, Japanese Olympic Committee president Tsunakazu Takeda, who had led Tokyo's bid, insisted the payments were for consulting work and did not raise suspicions among the campaign team at the time.

"We would like to reaffirm that the Olympic Games 2020 were awarded to Tokyo as the result of a fair competition and as a result of the contents of our bid," Takeda said in a statement. "The payments mentioned in the media were a legitimate consultant's fee."