Two Russian construction companies are reportedly using North Korean slave labor to prepare the city of St. Petersburg for the 2018 World Cup.

Exactly 110 North Korean forced laborers have worked on the Zenit Arena stadium in St. Petersburg, according to a report by Norwegian football magazine Josimar.

The laborers, who work for the St. Petersburg-based Seven Suns and Dalpiterstroy companies, work seven days a week, live in inhumane conditions and sleep in shipping containers. One of the workers was even found dead in a shipping container not far from the construction site, according to Josimar.

The Zenit stadium, near St. Petersburg's Krestovsky Ostrov metro station, has been under construction for 11 years. The project was initially intended as a new arena for the football team Zenit St. Petersburg and estimated to cost $220 million. However, after Russia's successful bid to host the World Cup, the stadium was assigned to be one of the championship's key venues. Since then, the cost of construction has skyrocketed to $1.5 billion and counting.