Hiroshi Igarashi has admitted Dentsu Group's involvement in bid rigging for Tokyo 2020 test events and competitions ©Getty Images

Dentsu Group President and chief executive Hiroshi Igarashi has admitted that the advertising agency was involved in rigging bids to plan pre-Games test events and operate competitions at the Tokyo 2020 Olympics and Paralympics.

The delayed Tokyo 2020 Games have been marred by a growing corruption scandal which also includes separate allegations of bribery.

In the latest development reported by Japanese news agency Kyodo, Igarashi admitted to Japanese prosecutors that Dentsu Group rigged bids for events in the build-up to and during Tokyo 2020.

Prosecutors are now considering charging Dentsu Group and five other companies for violating anti-monopoly rules, following complaints by the Japan Fair Trade Commission.

Kyodo reported that multiple people connected to Dentsu, including its former executive Koji Hemmi, had already admitted to the bid-rigging allegations.

It is claimed that officials from advertising agencies Hakuhodo and Tokyu Agency and event production companies Cerespo, Fuji Creative. and Same Two collaborated with Hemmi and Mori to rig 26 open bids in 2018 for the right to stage test events, which were awarded to nine companies including Dentsu, Hakuhodo and a consortium for a total of JPY 538 million (£3.3 million/$3.9 million/€3.7 million).

Corruption allegations including bid rigging and bribery have marred the delayed Tokyo 2020 Olympics and Paralympics ©Getty Images
Corruption allegations including bid rigging and bribery have marred the delayed Tokyo 2020 Olympics and Paralympics ©Getty Images

Successful companies are also suspected of reaching agreements to secure contracts for pre-Games test events and Tokyo 2020 competitions totalling JPY 40 billion (£245 million/$293 million/€278 million).

Cerespo has denied involvement, according to Kyodo.

Its event production executive Yoshiji Kamata and Fuji Creative's Masahiko Fujino were arrested along with Hemmi and Mori earlier this month.

Mori reportedly worked with Dentsu personnel to arrange successful bidders for test events, with prosecutors alleging he exchanged emails with companies to influence the process.

Corruption allegations have seriously damaged Japan's hopes of staging the 2030 Winter Olympics and Paralympics in Sapporo.

Former Tokyo 2020 Executive Board member Haruyuki Takahashi - also an ex-senior managing director at Dentsu – faces four charges of bribery which reportedly yielded JPY 198 million (£1.2 million/$1.5 million/€1.4 million) in return for helping companies secure sponsorship or marketing deals.

Former ADK Holdings President Shinichi Ueno last week admitted in court that he had bribed Takahashi.