A report released by a global union federation Wednesday demanded better conditions for laborers working on the construction of Tokyo Games facilities after several “alarming” cases of suspected labor violations were uncovered.

The report from Building and Wood Workers’ International (BWI), titled “The Dark Side of the Tokyo 2020 Summer Olympics,” is based on interviews with construction workers and documents how low pay, overwork and poor access to grievance mechanisms are creating a “culture of fear” among crews working on Olympic projects.

BWI, headquartered in Geneva, is seeking an end to “dangerous patterns of overwork,” citing the example of construction workers at the National Stadium and Olympic Village who reported being required to work up to 26 and 28 consecutive days, respectively.

“The Tokyo 2020 Summer Olympics was Japan’s opportunity to address some of the long-running gaps within the construction industry in Japan, however, these problems have just got worse,” BWI General Secretary Ambet Yuson said.

“Wages remain low, dangerous overwork is common, and workers have limited access to recourse to address their issues,” Yuson said.

RELATED STORIES Volunteers prepare to be the face of inclusive 2020 Tokyo Olympics

According to the report, the nation’s construction sector is facing an “acute labor shortage,” with 4.3 positions vacant for every worker. At the same time, an increase in construction activity has been driven by the hosting of the 2019 Rugby World Cup and 2020 Games, as well as ongoing reconstruction efforts in prefectures hit by the Great East Japan Earthquake and tsunami.

Among the findings, one case at the National Stadium was highlighted for being particularly grievous.

The report cited the rejection of a complaint about a worker’s injury because it had been brought by a union and not the injured party. The alleged rejection “constitutes a serious violation of the right to be represented, a core component of the right to freedom of association,” the federation said in the report.

The BWI sent a delegation to Tokyo last September to meet with key decision-makers and investigate the “conditions faced by workers in the construction of Tokyo 2020 Olympic facilities.”

Their findings were further substantiated by interviews conducted in February by BWI and its Japanese affiliate, the National Federation of Construction Workers’ Unions, with workers involved in the construction of the National Stadium and Olympic Village.

The report was sent Tuesday to the organizing committee of the Tokyo 2020 Olympics and Paralympics, the Tokyo Metropolitan Government and the Japan Sports Council — groups responsible for the construction of Olympic facilities. The 2020 organizing committee said Tuesday evening the report is “under review.”

Through their “Global Sports Campaign for Decent Work and Beyond,” the BWI has been examining large-scale international sporting events for over 10 years to “improve working conditions and ensure safety and health for workers building all projects related to mega-sporting events.”