Japanese agency Kyodo News reported that some companies were promised further contracts for operations at the Games if they were successful in their bids for planning the test events.

The Japan Fair Trade Commission and a special prosecution team in Tokyo are considering including both test events and those at the Games in their ongoing case.

Collusion has been linked to 26 open bids from May to August 2018, with these being awarded to nine companies including advertising companies Dentsu and Hakuhodo, sources told Kyodo News. 

Almost half of the 26 had just one bidder.

Last week, several officials at Dentsu admitted to bid rigging at Tokyo 2020 test events, after the company initially denied the allegations.

Kyodo News reported the same officials claimed they did not know what they were doing was an illegal act.

Dentsu, Hakuhodo and ADK Holdings, the three largest advertising agencies in Japan, have had their headquarters raided.

The corruption scandal became public knowledge in July 2022 when former Tokyo 2020 Organising Committee member Haruyuki Takahashi alleged to have accepted bribes for a total of JPY200 million (£1.2 million/$1.4 million/€1.3 million) from five companies.

It led to former Tokyo 2020 President and former Prime Minister of Japan, Yoshirō Mori, being questioned by prosecutors.

One of his connections was at publishing company Kadokawa Corporation, who were investigated too - leading to its chairman Tsuguhiko Kadokawa was detained by the Tokyo District Public Prosecutor's Office.

As a result, Sapporo's bid for the 2030 Winter Olympics has been put on hold, with two-thirds of the public in Hokkaido against the bid in light of the scandal.