The verdict, which comes at the same time as the emergence of fresh environmental concerns over materials being used to construct the venue, means his family will be entitled to compensation.

The unnamed worker allegedly clocked 200 hours of overtime at the stadium, the planned centrepiece for the 2020 Olympic and Paralympic Games, in the month before his body was found in April.

He went missing in March before being found with a note saying he had “reached the physical and mental limit”.

His family's lawyer, Hiroshi Kawahito, has now announced that the Shinjuku Labour determined that his case be formally recognised as a case of “karoshi”, or death from overwork.

“We strongly urge the prime contractor, the Olympics and Paralympics Organising Committee, the Tokyo Metropolitan Government and other parties concerned not to repeat such a tragedy,” Kawahito said in a statement published by the Japan Times.

“Karoshi” is blamed for hundreds of deaths each year from strokes, heart attacks or suicide in a country notorious for long working hours.

The suicide in December of an employee of advertising giants Dentsu generated growing concern after it emerged they had regularly logged more than 100 hours of monthly overtime.

Employers have since been requested by the Government to limit overtime to a maximum of 100 hours per month.

“We are relieved to see our son’s hard work recognised,” the worker's parents added in a statement. 

"We sincerely hope that the Tokyo Olympics and Paralympics will be held safely.”

It comes as the head an indigenous community has appealed to Japanese Prime Minister Shinzo Abe in an attempt to stop the use of wood that, he claims, is destroying their forests and livelihoods.

The head of the Penan community in Long Jaik in Borneo, Matu Tugang, is appealing against the use of tropical timber from a company in Sarawak in the stadium construction.

According to a statement from the Bruno Manser fund, published by FMT news, Tugang claimed in his letter that, so long as the contract continues, the company will continue “logging our forests and extracting logs daily”.

He claimed the company have been “logging our ancestral forests without our permission or consent" and that they have "never asked us for our opinion or needs”.

Tokyo 2020 have, however, already rejected such criticism.

“Tokyo 2020 had extensive discussions with working groups comprising experts in environmental matters, human rights, labour laws, corporate social responsibility and other fields,” a spokesman told Reuters last month following the expressing of initial concerns about this and other human rights matters.

“In the series of discussions, we decided to have the meetings fully open to the media.

“We even took in feedback from the public in order to establish the sourcing codes.”

The design for the new stadium, by architect Kengo Kuma, focuses upon a scaled-down, wood-rich Japanese-style interior decoration scheme.

It is due to cost ¥149 billion (£1.4 billion/$1.5 billion/€1.3 billion).