Dentsu has had its offices raided again as part of a corruption investigation ©Getty Images

Japanese prosecutors are again searching units of advertising agencies ADK Holdings and Dentsu, who are under suspicion of rigging bids for test events at the Tokyo 2020 Olympic Games.

Yesterday, the second-largest advertising agency Hakuhodo was raided for the first time.

Dentsu and ADK Holdings have had offices searched on Friday (November 25), with probes continuing into six companies.

A total of nine won the rights to the 56 test events.

Approximately half of the 26 test events had only one company make a bid, according to Kyodo News' source.

Event production companies Shimizu Octo and Tres were also searched in connection to the allegations.

These investigations cover the bidding process for test events at the Tokyo 2020 Olympic Games ©Getty Images
These investigations cover the bidding process for test events at the Tokyo 2020 Olympic Games ©Getty Images

ADK, the third-largest company in its industry, won three bids totalling JPY104,000,000 (£626,000/$751,000/€726,000), while Dentsu - the largest advertising agency in Japan - won one for JPY11,000,000 (£66,000/$79,000/€77,000).

Allegations cover possible collusion between Organising Committee members and companies trying to secure contracts without competition, with decisions being pre-determined.

ADK reported the alleged bid rigging to the Japan Fair Trade Commission after prosecutors launched the investigation.

These allegations suggest prior arrangements were made with Tokyo 2020 members before bidding was open.

First reports of corruption came when former Tokyo 2020 Organising Committee member Haruyuki Takahashi was alleged to have taken bribes to the tune of JPY200,000,000 (£1.2 million/$1.4 million/€1.3 million) from five companies.